Commit Graph

69 Commits

Author SHA1 Message Date
Martin Schwidefsky 72d38b1978 s390/vtime: correct scaled cputime of partially idle CPUs
The calculation for the SMT scaling factor for a hardware thread
which has been partially idle needs to disregard the cycles spent
by the other threads of the core while the thread is idle.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2015-09-30 16:22:38 +02:00
Martin Schwidefsky 61cc37906b s390/vtime: correct scaled cputime for SMT
The scaled cputime is supposed to be derived from the normal per-thread
cputime by dividing it with the average thread density in the last interval.

The calculation of the scaling values for the average thread density is
incorrect. The current, incorrect calculation:

    Ci = cycle count with i active threads
    T = unscaled cputime, sT = scaled cputime
    sT = T * (C1 + C2 + ... + Cn) / (1*C1 + 2*C2 + ... + n*Cn)

The calculation happens to yield the correct numbers for the simple cases
with only one Ci value not zero. But for cases with multiple Ci values not
zero it fails. E.g. on a SMT-2 system with one thread active half the time
and two threads active for the other half of the time it fails, the scaling
factor should be 3/4 but the formula gives 2/3.

The correct formula is

    sT = T * (C1/1 + C2/2 + ... + Cn/n) / (C1 + C2 + ... + Cn)

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2015-09-17 13:43:43 +02:00
Martin Schwidefsky f341b8dff9 s390/vtime: limit MT scaling value updates
The MT scaling values are updated on each calll to do_account_vtime.
This function is called for each HZ interrupt and for each context
switch. Context switch can happen often, the STCCTM instruction
on this path is noticeable. Limit the updates to once per jiffy.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2015-08-04 14:26:17 +02:00
Martin Schwidefsky 10ad34bc76 s390: add SMT support
The multi-threading facility is introduced with the z13 processor family.
This patch adds code to detect the multi-threading facility. With the
facility enabled each core will surface multiple hardware threads to the
system. Each hardware threads looks like a normal CPU to the operating
system with all its registers and properties.

The SCLP interface reports the SMT topology indirectly via the maximum
thread id. Each reported CPU in the result of a read-scp-information
is a core representing a number of hardware threads.

To reflect the reduced CPU capacity if two hardware threads run on a
single core the MT utilization counter set is used to normalize the
raw cputime obtained by the CPU timer deltas. This scaled cputime is
reported via the taskstats interface. The normal /proc/stat numbers
are based on the raw cputime and are not affected by the normalization.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2015-01-22 12:16:01 +01:00
Christian Borntraeger 032014bc04 s390/vtime: Get rid of redundant WARN_ON
in the cpu time accounting function vtime_account_irq_enter
(vtime_account_system) we use a WARN_ON_ONCE(!irqs_disabled()).
This is redundant as the function virt_timer_forward is always
called and has a BUG_ON(!irqs_disabled()).

This saves several nanoseconds in my specific testcase (KVM entry/exit)
and probably all other callers like (soft)irq entry/exit.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2014-12-18 09:55:56 +01:00
Martin Schwidefsky 1f759bb3a2 s390/time: use stck clock fast for do_account_vtime
The last high frequency call site of the STCK instruction is
do_account_vtime. Replace it with the faster STCKF instruction.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2014-10-27 13:27:01 +01:00
Martin Schwidefsky b5f87f15e2 s390/idle: consolidate idle functions and definitions
Move the C functions and definitions related to the idle state handling
to arch/s390/include/asm/idle.h and arch/s390/kernel/idle.c. The function
s390_get_idle_time is renamed to arch_cpu_idle_time and vtime_stop_cpu to
enabled_wait.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2014-10-09 09:14:03 +02:00
Martin Schwidefsky fe0f49768d s390/nohz: use a per-cpu flag for arch_needs_cpu
Move the nohz_delay bit from the s390_idle data structure to the
per-cpu flags. Clear the nohz delay flag in __cpu_disable and
remove the cpu hotplug notifier that used to do this.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2014-10-09 09:14:02 +02:00
Martin Schwidefsky 4560e7c331 s390/vtime: correct idle time calculation
Use the ACCESS_ONCE macro for both accesses to idle->sequence in the
loops to calculate the idle time. If only one access uses the macro,
the compiler is free to cache the value for the second access which
can cause endless loops.

Cc: stable@vger.kernel.org # 3.6+
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2013-10-31 09:52:52 +01:00
Martin Schwidefsky e258d719ff s390/uaccess: always run the kernel in home space
Simplify the uaccess code by removing the user_mode=home option.
The kernel will now always run in the home space mode.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2013-10-24 17:16:57 +02:00
Frederic Weisbecker a5725ac23b vtime: Describe overriden functions in dedicated arch headers
If the arch overrides some generic vtime APIs, let it describe
these on a dedicated and standalone header. This way it becomes
convenient to include it in vtime generic headers without irrelevant
stuff in such a low level header.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
2013-08-14 17:14:53 +02:00
Paul Gortmaker e2741f1758 s390: delete __cpuinit usage from all s390 files
The __cpuinit type of throwaway sections might have made sense
some time ago when RAM was more constrained, but now the savings
do not offset the cost and complications.  For example, the fix in
commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time")
is a good example of the nasty type of bugs that can be created
with improper use of the various __init prefixes.

After a discussion on LKML[1] it was decided that cpuinit should go
the way of devinit and be phased out.  Once all the users are gone,
we can then finally remove the macros themselves from linux/init.h.

Note that some harmless section mismatch warnings may result, since
notify_cpu_starting() and cpu_up() are arch independent (kernel/cpu.c)
are flagged as __cpuinit  -- so if we remove the __cpuinit from
arch specific callers, we will also get section mismatch warnings.
As an intermediate step, we intend to turn the linux/init.h cpuinit
content into no-ops as early as possible, since that will get rid
of these warnings.  In any case, they are temporary and harmless.

This removes all the arch/s390 uses of the __cpuinit macros from
all C files.  Currently s390 does not have any __CPUINIT used in
assembly files.

[1] https://lkml.org/lkml/2013/5/20/589

Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: linux390@de.ibm.com
Cc: linux-s390@vger.kernel.org
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2013-07-14 19:36:53 -04:00
Thomas Gleixner 52c0065947 s390: Use generic idle loop
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: Cc: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Magnus Damm <magnus.damm@gmail.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Link: http://lkml.kernel.org/r/20130321215235.090816526@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2013-04-08 17:39:27 +02:00
Linus Torvalds 81ec44a6c6 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux
Pull s390 update from Martin Schwidefsky:
 "The most prominent change in this patch set is the software dirty bit
  patch for s390.  It removes __HAVE_ARCH_PAGE_TEST_AND_CLEAR_DIRTY and
  the page_test_and_clear_dirty primitive which makes the common memory
  management code a bit less obscure.

  Heiko fixed most of the PCI related fallout, more often than not
  missing GENERIC_HARDIRQS dependencies.  Notable is one of the 3270
  patches which adds an export to tty_io to be able to resize a tty.

  The rest is the usual bunch of cleanups and bug fixes."

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (42 commits)
  s390/module: Add missing R_390_NONE relocation type
  drivers/gpio: add missing GENERIC_HARDIRQ dependency
  drivers/input: add couple of missing GENERIC_HARDIRQS dependencies
  s390/cleanup: rename SPP to LPP
  s390/mm: implement software dirty bits
  s390/mm: Fix crst upgrade of mmap with MAP_FIXED
  s390/linker skript: discard exit.data at runtime
  drivers/media: add missing GENERIC_HARDIRQS dependency
  s390/bpf,jit: add vlan tag support
  drivers/net,AT91RM9200: add missing GENERIC_HARDIRQS dependency
  iucv: fix kernel panic at reboot
  s390/Kconfig: sort list of arch selected config options
  phylib: remove !S390 dependeny from Kconfig
  uio: remove !S390 dependency from Kconfig
  dasd: fix sysfs cleanup in dasd_generic_remove
  s390/pci: fix hotplug module init
  s390/pci: cleanup clp page allocation
  s390/pci: cleanup clp inline assembly
  s390/perf: cpum_cf: fallback to software sampling events
  s390/mm: provide PAGE_SHARED define
  ...
2013-02-21 17:54:03 -08:00
Heiko Carstens 1aae0560d1 s390/time: rename tod clock access functions
Fix name clash with some common code device drivers and add "tod"
to all tod clock access function names.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2013-02-14 15:55:10 +01:00
Frederic Weisbecker 6a61671bb2 cputime: Safely read cputime of full dynticks CPUs
While remotely reading the cputime of a task running in a
full dynticks CPU, the values stored in utime/stime fields
of struct task_struct may be stale. Its values may be those
of the last kernel <-> user transition time snapshot and
we need to add the tickless time spent since this snapshot.

To fix this, flush the cputime of the dynticks CPUs on
kernel <-> user transition and record the time / context
where we did this. Then on top of this snapshot and the current
time, perform the fixup on the reader side from task_times()
accessors.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
[fixed kvm module related build errors]
Signed-off-by: Sedat Dilek <sedat.dilek@gmail.com>
2013-01-27 20:35:47 +01:00
Frederic Weisbecker 1b2852b152 vtime: Warn if irqs aren't disabled on system time accounting APIs
System time accounting APIs such as vtime_account_system() and
vtime_account_idle() need to be irqsafe. Current callers include
irq entry, exit and kvm, all of which have been checked against that
requirement. Now it's better to grow that with an automatic check
in case we have further callers or we missed something.

Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
2012-11-20 15:42:51 +01:00
Frederic Weisbecker bcebdf8465 vtime: Explicitly account pending user time on process tick
All vtime implementations just flush the user time on process
tick. Consolidate that in generic code by calling a user time
accounting helper. This avoids an indirect call in ia64 and
prepare to also consolidate vtime context switch code.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
2012-11-19 16:41:21 +01:00
Frederic Weisbecker fd25b4c2f2 vtime: Remove the underscore prefix invasion
Prepending irq-unsafe vtime APIs with underscores was actually
a bad idea as the result is a big mess in the API namespace that
is even waiting to be further extended. Also these helpers
are always called from irq safe callers except kvm. Just
provide a vtime_account_system_irqsafe() for this specific
case so that we can remove the underscore prefix on other
vtime functions.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
2012-11-19 16:40:16 +01:00
Frederic Weisbecker 11113334d1 vtime: Make vtime_account_system() irqsafe
vtime_account_system() currently has only one caller with
vtime_account() which is irq safe.

Now we are going to call it from other places like kvm where
irqs are not always disabled by the time we account the cputime.

So let's make it irqsafe. The arch implementation part is now
prefixed with "__".

vtime_account_idle() arch implementation is prefixed accordingly
to stay consistent.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
2012-10-29 21:31:31 +01:00
Linus Torvalds 6c09931b3f Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux
Pull s390 updates from Martin Schwidefsky:
 "The main new feature is machine support for System zEC12 including
  transactional memory, runtime instrumentation, support for scm block
  devices via eadm subchannels, and support for CEX4 crypto cards.

  In addition there are some nice improvements: bpf jit compiler, arch
  backend for cmpxchg_double, relative exception table entries, dasd
  partition detection independent from the dasd driver ioctls, and cpu
  cache information in /proc/cpuinfo and /sys/device/cpu.

  And last but not least a series of cleanup patches from Heiko."

Fix up trivial add-add conflict in arch/s390/Kconfig due to commit
b952741c80 ("cputime: Generalize CONFIG_VIRT_CPU_ACCOUNTING")

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (76 commits)
  s390: update defconfig
  s390/jump label,nss: let shared kernel support depend on !JUMP_LABEL
  s390/disassembler: fix decoding of risblg instruction
  s390/bpf,jit: add support for BPF_S_ANC_ALU_XOR_X instruction
  s390/traps: move call to print_modules() out of show_regs()
  s390/mm: mark free_initrd_mem() as __init
  s390/dasd: check count address during online setting
  drivers/s390/char/monreader.c: fix error return code
  s390/cmpxchg,percpu: implement cmpxchg_double()
  s390/percpu: implement this_cpu_add_return()
  s390/percpu: implement this_cpu_xchg()
  s390/kexec: remove CONFIG_KEXEC
  s390/irq: use designated initializers for irq class array
  s390: add uninitialized_var() to suppress false positive compiler warnings
  s390/crashdump: move fill_cpu_elf_notes() prototype to header file
  s390/process: add missing header include
  s390/ptrace: add missing ifdef
  s390/ipl,decrompressor: disable branch profiling
  s390/perf_events: compile only for CONFIG_64BIT
  s390/tape: remove even more tape block leftovers
  ...
2012-10-01 11:49:56 -07:00
Heiko Carstens 1c725922dd s390/cpu hotplug: mask out CPU_TASKS_FROZEN in cu hotplug notifiers
Unify all our cpu hotplug notifiers to mask out the CPU_TASKS_FROZEN
bit, so we don't have to add all the *_FROZEN variant cases to the
notifiers.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-09-26 15:44:53 +02:00
Frederic Weisbecker bf9fae9f5e cputime: Use a proper subsystem naming for vtime related APIs
Use a naming based on vtime as a prefix for virtual based
cputime accounting APIs:

- account_system_vtime() -> vtime_account()
- account_switch_vtime() -> vtime_task_switch()

It makes it easier to allow for further declension such
as vtime_account_system(), vtime_account_idle(), ... if we
want to find out the context we account to from generic code.

This also make it better to know on which subsystem these APIs
refer to.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
2012-09-25 15:31:31 +02:00
Frederic Weisbecker baa36046d0 cputime: Consolidate vtime handling on context switch
The archs that implement virtual cputime accounting all
flush the cputime of a task when it gets descheduled
and sometimes set up some ground initialization for the
next task to account its cputime.

These archs all put their own hooks in their context
switch callbacks and handle the off-case themselves.

Consolidate this by creating a new account_switch_vtime()
callback called in generic code right after a context switch
and that these archs must implement to flush the prev task
cputime and initialize the next task cputime related state.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
2012-08-20 13:05:28 +02:00
Martin Schwidefsky 27f6b41662 s390/vtimer: rework virtual timer interface
The current virtual timer interface is inherently per-cpu and hard to
use. The sole user of the interface is appldata which uses it to execute
a function after a specific amount of cputime has been used over all cpus.

Rework the virtual timer interface to hook into the cputime accounting.
This makes the interface independent from the CPU timer interrupts, and
makes the virtual timers global as opposed to per-cpu.
Overall the code is greatly simplified. The downside is that the accuracy
is not as good as the original implementation, but it is still good enough
for appldata.

Reviewed-by: Jan Glauber <jang@linux.vnet.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-07-20 11:15:08 +02:00
Heiko Carstens fde15c3a3a [S390] irq: external interrupt code passing
The external interrupt handlers have a parameter called ext_int_code.
Besides the name this paramter does not only contain the ext_int_code
but in addition also the "cpu address" (POP) which caused the external
interrupt.
To make the code a bit more obvious pass a struct instead so the called
function can easily distinguish between external interrupt code and
cpu address. The cpu address field however is named "subcode" since
some external interrupt sources do not pass a cpu address but a
different parameter (or none at all).

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-03-11 11:59:29 -04:00
Martin Schwidefsky 4c1051e37a [S390] rework idle code
Whenever the cpu loads an enabled wait PSW it will appear as idle to the
underlying host system. The code in default_idle calls vtime_stop_cpu
which does the necessary voodoo to get the cpu time accounting right.
The udelay code just loads an enabled wait PSW. To correct this rework
the vtime_stop_cpu/vtime_start_cpu logic and move the difficult parts
to entry[64].S, vtime_stop_cpu can now be called from anywhere and
vtime_start_cpu is gone. The correction of the cpu time during wakeup
from an enabled wait PSW is done with a critical section in entry[64].S.
As vtime_start_cpu is gone, s390_idle_check can be removed as well.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-03-11 11:59:28 -04:00
Martin Schwidefsky 8b646bd759 [S390] rework smp code
Define struct pcpu and merge some of the NR_CPUS arrays into it, including
__cpu_logical_map, current_set and smp_cpu_state. Split smp related
functions to those operating on physical cpus and the functions operating
on a logical cpu number. Make the functions for physical cpus use a
pointer to a struct pcpu. This hides the knowledge about cpu addresses in
smp.c, entry[64].S and swsusp_asm64.S, thus remove the sigp.h header.

The PSW restart mechanism is used to start secondary cpus, calling a
function on an online cpu, calling a function on the ipl cpu, and for
the nmi signal. Replace the different assembler functions with a
single function restart_int_handler. The new entry point calls a function
whose pointer is stored in the lowcore of the target cpu and it can wait
for the source cpu to stop. This covers all existing use cases.

Overall the code is now simpler and there are ~380 lines less code.

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-03-11 11:59:28 -04:00
Martin Schwidefsky c4736d9682 [S390] sparse: fix sparse static warnings
Make functions and data static to avoid sparse warnings.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2011-10-30 15:16:46 +01:00
Martin Schwidefsky b50511e41a [S390] cleanup psw related bits and pieces
Split out addressing mode bits from PSW_BASE_BITS, rename PSW_BASE_BITS
to PSW_MASK_BASE, get rid of psw_user32_bits, remove unused function
enabled_wait(), introduce PSW_MASK_USER, and drop PSW_MASK_MERGE macros.
Change psw_kernel_bits / psw_user_bits to contain only the bits that
are always set in the respective mode.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2011-10-30 15:16:43 +01:00
Heiko Carstens d7b250e2a2 [S390] irq: merge irq.c and s390_ext.c
Merge irq.c and s390_ext.c into irq.c. That way all external interrupt
related functions are together.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2011-05-26 09:48:24 +02:00
Lucas De Marchi 25985edced Fix common misspellings
Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
2011-03-31 11:26:23 -03:00
Heiko Carstens 052ff461c8 [S390] irq: have detailed statistics for interrupt types
Up to now /proc/interrupts only has statistics for external and i/o
interrupts but doesn't split up them any further.
This patch adds a line for every single interrupt source so that it
is possible to easier tell what the machine is/was doing.
Part of the output now looks like this;

           CPU0       CPU2       CPU4
EXT:       3898       4232       2305
I/O:        782        315        245
CLK:       1029       1964        727   [EXT] Clock Comparator
IPI:       2868       2267       1577   [EXT] Signal Processor
TMR:          0          0          0   [EXT] CPU Timer
TAL:          0          0          0   [EXT] Timing Alert
PFL:          0          0          0   [EXT] Pseudo Page Fault
[...]
NMI:          0          1          1   [NMI] Machine Checks

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2011-01-05 12:47:25 +01:00
Martin Schwidefsky 860dba45e8 [S390] add kprobes annotations
Add kprobes annotations to get the massive 'probe kernel.function("*") {}'
stress test working.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2011-01-05 12:47:24 +01:00
Heiko Carstens 398812159e [S390] nohz/s390: fix arch_needs_cpu() return value on offline cpus
This fixes the same problem as described in the patch "nohz: fix
printk_needs_cpu() return value on offline cpus" for the arch_needs_cpu()
primitive:

arch_needs_cpu() may return 1 if called on offline cpus. When a cpu gets
offlined it schedules the idle process which, before killing its own cpu,
will call tick_nohz_stop_sched_tick().
That function in turn will call arch_needs_cpu() in order to check if the
local tick can be disabled. On offline cpus this function should naturally
return 0 since regardless if the tick gets disabled or not the cpu will be
dead short after. That is besides the fact that __cpu_disable() should already
have made sure that no interrupts on the offlined cpu will be delivered anyway.

In this case it prevents tick_nohz_stop_sched_tick() to call
select_nohz_load_balancer(). No idea if that really is a problem. However what
made me debug this is that on 2.6.32 the function get_nohz_load_balancer() is
used within __mod_timer() to select a cpu on which a timer gets enqueued.
If arch_needs_cpu() returns 1 then the nohz_load_balancer cpu doesn't get
updated when a cpu gets offlined. It may contain the cpu number of an offline
cpu. In turn timers get enqueued on an offline cpu and not very surprisingly
they never expire and cause system hangs.

This has been observed 2.6.32 kernels. On current kernels __mod_timer() uses
get_nohz_timer_target() which doesn't have that problem. However there might
be other problems because of the too early exit tick_nohz_stop_sched_tick()
in case a cpu goes offline.

This specific bug was indrocuded with 3c5d92a0 "nohz: Introduce
arch_needs_cpu".

In this case a cpu hotplug notifier is used to fix the issue in order to keep
the normal/fast path small. All we need to do is to clear the condition that
makes arch_needs_cpu() return 1 since it is just a performance improvement
which is supposed to keep the local tick running for a short period if a cpu
goes idle. Nothing special needs to be done except for clearing the condition.

Cc: stable@kernel.org
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2010-12-01 10:08:17 +01:00
Martin Schwidefsky f6649a7e5a [S390] cleanup lowcore access from external interrupts
Read external interrupts parameters from the lowcore in the first
level interrupt handler in entry[64].S.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2010-10-25 16:10:19 +02:00
Martin Schwidefsky 6377981faf [S390] idle time accounting vs. machine checks
A machine check can interrupt the i/o and external interrupt handler
anytime. If the machine check occurs while the interrupt handler is
waking up from idle vtime_start_cpu can get executed a second time
and the int_clock / async_enter_timer values in the lowcore get
clobbered. This can confuse the cpu time accounting.
To fix this problem two changes are needed. First the machine check
handler has to use its own copies of int_clock and async_enter_timer,
named mcck_clock and mcck_enter_timer. Second the nested execution
of vtime_start_cpu has to be prevented. This is done in s390_idle_check
by checking the wait bit in the program status word.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2010-05-17 10:00:15 +02:00
Martin Schwidefsky 3c5d92a0cf nohz: Introduce arch_needs_cpu
Allow the architecture to request a normal jiffy tick when the system
goes idle and tick_nohz_stop_sched_tick is called . On s390 the hook is
used to prevent the system going fully idle if there has been an
interrupt other than a clock comparator interrupt since the last wakeup.

On s390 the HiperSockets response time for 1 connection ping-pong goes
down from 42 to 34 microseconds. The CPU cost decreases by 27%.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
LKML-Reference: <20090929122533.402715150@de.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2009-11-05 07:53:53 +01:00
Martin Schwidefsky e98bbaafcd [S390] lockless idle time accounting
Replace the spinlock used in the idle time accounting with a sequence
counter mechanism analog to seqlock.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2009-06-22 12:08:23 +02:00
Heiko Carstens d7d1104fa4 [S390] time: convert from bootmem to slab
The slab allocator is earlier available so convert the
bootmem allocations to slab/gfp allocations.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2009-06-22 12:08:16 +02:00
Martin Schwidefsky 76d4e00a05 [S390] merge cpu.h into cputime.h
All definition in cpu.h have to do with cputime accounting. Move
them to cputime.h and remove the header file.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2009-06-12 10:27:29 +02:00
Martin Schwidefsky e1c805309d [S390] /proc/stat idle field for idle cpus
The cpu idle field in the output of /proc/stat is too small for cpus
that have been idle for more than a tick. Add the architecture hook
arch_idle_time that allows to add the not accounted idle time of a
sleeping cpu without waking the cpu.

The s390 implementation of arch_idle_time uses the already existing
s390_idle_data per_cpu variable to find the sleep time of a neighboring
idle cpu.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2009-04-23 13:58:17 +02:00
Martin Schwidefsky ab96e798cb [S390] boot cputime accounting
Start the cpu time accounting very early to catch the cpu time spent
for the initial kernel setup. To make the output of /proc/uptime
match the sum of all cpu accounting values of the boot cpu reset
xtime and wall_to_monotonic to sane values based on the TOD clock.
The values set by timekeeping_init are off by up to a second.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2009-04-14 15:37:27 +02:00
Martin Schwidefsky b86ccca49c [S390] fix idle time accounting
The steal time is calculated by subtracting the time the virtual cpu
has been running on a physical cpu from the wall clock time. To make
that work all wall time needs to be added to the steal time field first
before the virtual cpu time is subtracted.

The time between the last clock update and the load of the enabled wait
psw needs to be added to the steal_time field as well to make the sum
over all cpu accounting numbers match the wall clock.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2009-04-14 15:37:26 +02:00
Jan Glauber b6ecfa9273 [S390] extend virtual timer interface by mod_virt_timer_periodic
In case mod_virt_timer is used to add a non pending timer the timer
is always added as a one-shot timer. If mod_virt_timer is used for
periodic timers they may therfore be degraded to one-shot timers.

Add mod_virt_timer_periodic to the interface to allow safe re-programming
of the interval value.

Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2009-04-14 15:37:23 +02:00
Heiko Carstens f9a2f797fc [S390] cputime: fix lowcore initialization on cpu hotplug
On (initial) cpu hotplug the lowcore values for user_timer and
system_timer don't get initialized like they would get on each
process schedule.
On initial start of secondary cpus this leads to the situation
where per thread user/system_timer values are larger than the
corresponding contents of the lowcore. When later calculating
time spent in user/system context the result can be negative.

So for cpu hotplug we should manually initialize lowcore values.

Fixes this bug:

Kernel BUG at 000ec080 [verbose debug info unavailable]
fixpoint divide exception: 0009 [#1] PREEMPT SMP
Modules linked in:
CPU: 10 Not tainted 2.6.28 #4
Process sysctl (pid: 975, task: 3fa752e0, ksp: 3fbebca0)
Krnl PSW : 070c1000 800ec080 (show_stat+0x390/0x5fc)
           R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:0 CC:1 PM:0
Krnl GPRS: 7fffffff fefc7ce5 3faec080 003879ae
           00000001 01388000 7fffffff 01388000
           00000000 00000000 0049ad50 3fbebcf8
           01388000 002f51a8 800ec1fe 3fbebcf8
Krnl Code: 800ec076: 9001b188           stm     %r0,%r1,392(%r11)
           800ec07a: 9801b0c0           lm      %r0,%r1,192(%r11)
           800ec07e: 1d05               dr      %r0,%r5
          >800ec080: 9001b0c0           stm     %r0,%r1,192(%r11)
           800ec084: 5860b0c4           l       %r6,196(%r11)
           800ec088: 1806               lr      %r0,%r6
           800ec08a: 8c800001           srdl    %r8,1
           800ec08e: 1d87               dr      %r8,%r7
Call Trace:
([<00000000000ec1ee>] show_stat+0x4fe/0x5fc)
 [<00000000000c13e8>] seq_read+0xc4/0x3ac
 [<00000000000e4796>] proc_reg_read+0x6e/0x9c
 [<00000000000a6a44>] vfs_read+0x78/0x100
 [<00000000000a6ba8>] sys_read+0x40/0x80
 [<00000000000234a8>] sysc_do_restart+0x1a/0x1e

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
2009-01-23 16:40:28 +01:00
Martin Schwidefsky 9cfb9b3c3a [PATCH] improve idle cputime accounting
Distinguish the cputime of the idle process where idle is actually using
cpu cycles from the cputime where idle is sleeping on an enabled wait psw.
The former is accounted as system time, the later as idle time.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2008-12-31 15:11:48 +01:00
Martin Schwidefsky 6f43092441 [PATCH] improve precision of idle time detection.
Increase the precision of the idle time calculation that is exported
to user space via /sys/devices/system/cpu/cpu<x>/idle_time_us

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2008-12-31 15:11:47 +01:00
Martin Schwidefsky aa5e97ce4b [PATCH] improve precision of process accounting.
The unit of the cputime accouting values that are stored per process is
currently a microsecond. The CPU timer has a maximum granularity of
2**-12 microseconds. There is no benefit in storing the per process values
in the lesser precision and there is the disadvantage that the backend
has to do the rounding to microseconds. The better solution is to use
the maximum granularity of the CPU timer as cputime unit.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2008-12-31 15:11:47 +01:00
Martin Schwidefsky 79741dd357 [PATCH] idle cputime accounting
The cpu time spent by the idle process actually doing something is
currently accounted as idle time. This is plain wrong, the architectures
that support VIRT_CPU_ACCOUNTING=y can do better: distinguish between the
time spent doing nothing and the time spent by idle doing work. The first
is accounted with account_idle_time and the second with account_system_time.
The architectures that use the account_xxx_time interface directly and not
the account_xxx_ticks interface now need to do the check for the idle
process in their arch code. In particular to improve the system vs true
idle time accounting the arch code needs to measure the true idle time
instead of just testing for the idle process.
To improve the tick based accounting as well we would need an architecture
primitive that can tell us if the pt_regs of the interrupted context
points to the magic instruction that halts the cpu.

In addition idle time is no more added to the stime of the idle process.
This field now contains the system time of the idle process as it should
be. On systems without VIRT_CPU_ACCOUNTING this will always be zero as
every tick that occurs while idle is running will be accounted as idle
time.

This patch contains the necessary common code changes to be able to
distinguish idle system time and true idle time. The architectures with
support for VIRT_CPU_ACCOUNTING need some changes to exploit this.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2008-12-31 15:11:46 +01:00