Commit Graph

312 Commits

Author SHA1 Message Date
Matthias Kaehlcke 70cee26e02 Use list_for_each_entry() instead of list_for_each() in the block device
elevator

Signed-off-by: Matthias Kaehlcke <matthias.kaehlcke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-10 13:43:32 +02:00
Jan Engelhardt 16ed002f22 Use menuconfigs instead of menus, so the whole menu can be disabled at once
instead of going through all options.

Signed-off-by: Jan Engelhardt <jengelh@gmx.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-10 13:43:27 +02:00
Jens Axboe 15c31be4d5 cfq-iosched: fix async queue behaviour
With the cfq_queue hash removal, we inadvertently got rid of the
async queue sharing. This was not intentional, in fact CFQ purposely
shares the async queue per priority level to get good merging for
async writes.

So put some logic in cfq_get_queue() to track the shared queues.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-10 13:43:25 +02:00
Tejun Heo f4b09303d0 [BLOCK] drop unnecessary bvec rewinding from flush_dry_bio_endio
Barrier bios are completed twice - once after the barrier write itself
is done and again after the whole sequence is complete.
flush_dry_bio_endio() is for the first completion.  It doesn't really
complete the bio.  It rewinds bvec and resets bio so that it can be
completed again when the whole barrier sequence is complete.

The bvec rewinding code has the following problems.

1. The rewinding code is wrong because filesystems may pass bvec with
   non zero bv_offset.

2. The block layer doesn't guarantee anything about the state of
   bvec array on request completion.  bv_offset and len are updated
   iff __end_that_request_first() completes the bvec partially.

Because of #2, #1 doesn't really matter (nobody cares whether bvec is
re-wound correctly or not) but then again by not doing unwinding at
all, we'll always give back the same bvec to the caller as full bvec
completion doesn't alter bvecs and the final completion is always full
completion.

Drop unnecessary rewinding code.

This is spotted by Neil Brown.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-10 08:03:33 +02:00
Jens Axboe 32eef96411 blk_hw_contig_segment(): bad segment size checks
Two bugs in there:

- The virt oversize check should use the current bio hardware back
  size and the next bio front size, not the same bio. Spotted by
  Neil Brown.

- The segment size check should add hw front sizes, not total bio
  sizes. Spotted by James Bottomley

Acked-by: James Bottomley <James.Bottomley@SteelEye.com>
Acked-by: NeilBrown <neilb@suse.de>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-10 08:03:32 +02:00
Tejun Heo bc90ba093a block: always requeue !fs requests at the front
SCSI marks internal commands with REQ_PREEMPT and push it at the front
of the request queue using blk_execute_rq().  When entering suspended
or frozen state, SCSI devices are quiesced using
scsi_device_quiesce().  In quiesced state, only REQ_PREEMPT requests
are processed.  This is how SCSI blocks other requests out while
suspending and resuming.  As all internal commands are pushed at the
front of the queue, this usually works.

Unfortunately, this interacts badly with ordered requeueing.  To
preserve request order on requeueing (due to busy device, active EH or
other failures), requests are sorted according to ordered sequence on
requeue if IO barrier is in progress.

The following sequence deadlocks.

1. IO barrier sequence issues.

2. Suspend requested.  Queue is quiesced with part or all of IO
   barrier sequence at the front.

3. During suspending or resuming, SCSI issues internal command which
   gets deferred and requeued for some reason.  As the command is
   issued after the IO barrier in #1, ordered requeueing code puts the
   request after IO barrier sequence.

4. The device is ready to process requests again but still is in
   quiesced state and the first request of the queue isn't
   REQ_PREEMPT, so command processing is deadlocked -
   suspending/resuming waits for the issued request to complete while
   the request can't be processed till device is put back into
   running state by resuming.

This can be fixed by always putting !fs requests at the front when
requeueing.

The following thread reports this deadlock.

  http://thread.gmane.org/gmane.linux.kernel/537473

Signed-off-by: Tejun Heo <htejun@gmail.com>
Acked-by: David Greaves <david@dgreaves.com>
Acked-by: Jeff Garzik <jeff@garzik.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-06-15 16:12:20 -07:00
Kristen Carlson Accardi 8ce7ad7b2d genhd: send async notification on media change
Send an uevent to user space to indicate that a media change event has
occurred.

Signed-off-by: Kristen Carlson Accardi <kristen.c.accardi@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-23 20:14:12 -07:00
Kristen Carlson Accardi 86ce18d7b7 genhd: expose AN to user space
Allow user space to determine if a disk supports Asynchronous Notification of
media changes.  This is done by adding a new sysfs file "capability_flags",
which is documented in (insert file name).  This sysfs file will export all
disk capabilities flags to user space.  We also define a new flag to define
the media change notification capability.

Signed-off-by: Kristen Carlson Accardi <kristen.c.accardi@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-23 20:14:11 -07:00
Jens Axboe f653c34dd3 ll_rw_blk: fix gcc 4.2 warning on current_io_context()
current_io_context() is both static and exported with EXPORT_SYMBOL().
As there are no users outside of ll_rw_blk.c itself, just kill the
export.

Problem reported by Martin Michlmayr <tbm@cyrius.com>

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-15 10:44:15 -07:00
Neil Brown d89d87965d When stacked block devices are in-use (e.g. md or dm), the recursive calls
to generic_make_request can use up a lot of space, and we would rather they
didn't.

As generic_make_request is a void function, and as it is generally not
expected that it will have any effect immediately, it is safe to delay any
call to generic_make_request until there is sufficient stack space
available.

As ->bi_next is reserved for the driver to use, it can have no valid value
when generic_make_request is called, and as __make_request implicitly
assumes it will be NULL (ELEVATOR_BACK_MERGE fork of switch) we can be
certain that all callers set it to NULL.  We can therefore safely use
bi_next to link pending requests together, providing we clear it before
making the real call.

So, we choose to allow each thread to only be active in one
generic_make_request at a time.  If a subsequent (recursive) call is made,
the bio is linked into a per-thread list, and is handled when the active
call completes.

As the list of pending bios is per-thread, there are no locking issues to
worry about.

I say above that it is "safe to delay any call...".  There are, however,
some behaviours of a make_request_fn which would make it unsafe.  These
include any behaviour that assumes anything will have changed after a
recursive call to generic_make_request.

These could include:
 - waiting for that call to finish and call it's bi_end_io function.
   md use to sometimes do this (marking the superblock dirty before
   completing a write) but doesn't any more
 - inspecting the bio for fields that generic_make_request might
   change, such as bi_sector or bi_bdev.  It is hard to see a good
   reason for this, and I don't think anyone actually does it.
 - inspecing the queue to see if, e.g. it is 'full' yet.  Again, I
   think this is very unlikely to be useful, or to be done.

Signed-off-by: Neil Brown <neilb@suse.de>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <dm-devel@redhat.com>

Alasdair G Kergon <agk@redhat.com> said:

 I can see nothing wrong with this in principle.

 For device-mapper at the moment though it's essential that, while the bio
 mappings may now get delayed, they still get processed in exactly
 the same order as they were passed to generic_make_request().

 My main concern is whether the timing changes implicit in this patch
 will make the rare data-corrupting races in the existing snapshot code
 more likely. (I'm working on a fix for these races, but the unfinished
 patch is already several hundred lines long.)

 It would be helpful if some people on this mailing list would test
 this patch in various scenarios and report back.

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-05-11 13:28:37 +02:00
Linus Torvalds 9a9136e270 Merge git://git.kernel.org/pub/scm/linux/kernel/git/bunk/trivial
* git://git.kernel.org/pub/scm/linux/kernel/git/bunk/trivial: (25 commits)
  sound: convert "sound" subdirectory to UTF-8
  MAINTAINERS: Add cxacru website/mailing list
  include files: convert "include" subdirectory to UTF-8
  general: convert "kernel" subdirectory to UTF-8
  documentation: convert the Documentation directory to UTF-8
  Convert the toplevel files CREDITS and MAINTAINERS to UTF-8.
  remove broken URLs from net drivers' output
  Magic number prefix consistency change to Documentation/magic-number.txt
  trivial: s/i_sem /i_mutex/
  fix file specification in comments
  drivers/base/platform.c: fix small typo in doc
  misc doc and kconfig typos
  Remove obsolete fat_cvf help text
  Fix occurrences of "the the "
  Fix minor typoes in kernel/module.c
  Kconfig: Remove reference to external mqueue library
  Kconfig: A couple of grammatical fixes in arch/i386/Kconfig
  Correct comments in genrtc.c to refer to correct /proc file.
  Fix more "deprecated" spellos.
  Fix "deprecated" typoes.
  ...

Fix trivial comment conflict in kernel/relay.c.
2007-05-09 12:54:17 -07:00
Rafael J. Wysocki 8bb7844286 Add suspend-related notifications for CPU hotplug
Since nonboot CPUs are now disabled after tasks and devices have been
frozen and the CPU hotplug infrastructure is used for this purpose, we need
special CPU hotplug notifications that will help the CPU-hotplug-aware
subsystems distinguish normal CPU hotplug events from CPU hotplug events
related to a system-wide suspend or resume operation in progress.  This
patch introduces such notifications and causes them to be used during
suspend and resume transitions.  It also changes all of the
CPU-hotplug-aware subsystems to take these notifications into consideration
(for now they are handled in the same way as the corresponding "normal"
ones).

[oleg@tv-sign.ru: cleanups]
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-09 12:30:56 -07:00
Oleg Nesterov 28e53bddf8 unify flush_work/flush_work_keventd and rename it to cancel_work_sync
flush_work(wq, work) doesn't need the first parameter, we can use cwq->wq
(this was possible from the very beginnig, I missed this).  So we can unify
flush_work_keventd and flush_work.

Also, rename flush_work() to cancel_work_sync() and fix all callers.
Perhaps this is not the best name, but "flush_work" is really bad.

(akpm: this is why the earlier patches bypassed maintainers)

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Jeff Garzik <jeff@garzik.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Tejun Heo <htejun@gmail.com>
Cc: Auke Kok <auke-jan.h.kok@intel.com>,
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-09 12:30:53 -07:00
Andrew Morton 19a75d83ff kblockd: use flush_work
Switch the kblockd flushing from a global flush to a more specific
flush_work().

(akpm: bypassed maintainers, sorry.  There are other patches which depend on
this)

Cc: "Maciej W. Rozycki" <macro@linux-mips.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Jens Axboe <axboe@suse.de>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-09 12:30:51 -07:00
Dave Gilbert dd2a345f8f Display all possible partitions when the root filesystem failed to mount
Display all possible partitions when the root filesystem is not mounted.
This helps to track spell'o's and missing drivers.

Updated to work with newer kernels.

Example output:

VFS: Cannot open root device "foobar" or unknown-block(0,0)
Please append a correct "root=" boot option; here are the available partitions:
0800    8388608 sda driver: sd
  0801     192748 sda1
  0802    8193150 sda2
0810    4194304 sdb driver: sd
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)

[akpm@linux-foundation.org: cleanups, fix printk warnings]
Signed-off-by: Jan Engelhardt <jengelh@gmx.de>
Cc: Dave Gilbert <linux@treblig.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-09 12:30:48 -07:00
Michael Opdenacker 59c51591a0 Fix occurrences of "the the "
Signed-off-by: Michael Opdenacker <michael@free-electrons.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
2007-05-09 08:57:56 +02:00
Linus Torvalds 02a93208ed Merge branch 'for-2.6.22' of git://git.kernel.dk/data/git/linux-2.6-block
* 'for-2.6.22' of git://git.kernel.dk/data/git/linux-2.6-block:
  [PATCH] ll_rw_blk: fix missing bounce in blk_rq_map_kern()
  [PATCH] splice: always call into page_cache_readahead()
  [PATCH] splice(): fix interaction with readahead
2007-05-08 11:34:52 -07:00
Nick Piggin c6a632a2b6 as: fix antic_expire check
Fix units mismatch (jiffies vs msecs) in as-iosched.c, spotted by Xiaoning
Ding <dingxn@cse.ohio-state.edu>.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08 11:15:03 -07:00
Mike Christie 821de3a27b [PATCH] ll_rw_blk: fix missing bounce in blk_rq_map_kern()
I think we might just need the blk_map_kern users now. For the async
execute I added the bounce code already and the block SG_IO has it
atleady. I think the blk_map_kern bounce code got dropped because we
thought the correct gfp_t would be passed in. But I think all we need is
the patch below and all the paths are take care of. The patch is not
tested. Patch was made against scsi-misc.

The last place that is sending non sg commands may just be md/dm-emc.c
but that is is just waiting on alasdair to take some patches that fix
that and a bunch of junk in there including adding bounce support. If
the patch below is ok though and dm-emc finally gets converted then it
will have sg and bonce buffer support.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-05-08 19:12:23 +02:00
Christoph Lameter 0a31bd5f2b KMEM_CACHE(): simplify slab cache creation
This patch provides a new macro

KMEM_CACHE(<struct>, <flags>)

to simplify slab creation. KMEM_CACHE creates a slab with the name of the
struct, with the size of the struct and with the alignment of the struct.
Additional slab flags may be specified if necessary.

Example

struct test_slab {
	int a,b,c;
	struct list_head;
} __cacheline_aligned_in_smp;

test_slab_cache = KMEM_CACHE(test_slab, SLAB_PANIC)

will create a new slab named "test_slab" of the size sizeof(struct
test_slab) and aligned to the alignment of test slab.  If it fails then we
panic.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-07 12:12:55 -07:00
Peter Zijlstra f98393a64c mm: remove destroy_dirty_buffers from invalidate_bdev()
Remove the destroy_dirty_buffers argument from invalidate_bdev(), it hasn't
been used in 6 years (so akpm says).

find * -name \*.[ch] | xargs grep -l invalidate_bdev |
while read file; do
	quilt add $file;
	sed -ie 's/invalidate_bdev(\([^,]*\),[^)]*)/invalidate_bdev(\1)/g' $file;
done

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-07 12:12:55 -07:00
Linus Torvalds 4f7a307dc6 Merge master.kernel.org:/pub/scm/linux/kernel/git/jejb/scsi-misc-2.6
* master.kernel.org:/pub/scm/linux/kernel/git/jejb/scsi-misc-2.6: (87 commits)
  [SCSI] fusion: fix domain validation loops
  [SCSI] qla2xxx: fix regression on sparc64
  [SCSI] modalias for scsi devices
  [SCSI] sg: cap reserved_size values at max_sectors
  [SCSI] BusLogic: stop using check_region
  [SCSI] tgt: fix rdma transfer bugs
  [SCSI] aacraid: fix aacraid not finding device
  [SCSI] aacraid: Correct SMC products in aacraid.txt
  [SCSI] scsi_error.c: Add EH Start Unit retry
  [SCSI] aacraid: [Fastboot] Panics for AACRAID driver during 'insmod' for kexec test.
  [SCSI] ipr: Driver version to 2.3.2
  [SCSI] ipr: Faster sg list fetch
  [SCSI] ipr: Return better qc_issue errors
  [SCSI] ipr: Disrupt device error
  [SCSI] ipr: Improve async error logging level control
  [SCSI] ipr: PCI unblock config access fix
  [SCSI] ipr: Fix for oops following SATA request sense
  [SCSI] ipr: Log error for SAS dual path switch
  [SCSI] ipr: Enable logging of debug error data for all devices
  [SCSI] ipr: Add new PCI-E IDs to device table
  ...
2007-05-05 13:30:44 -07:00
Greg Kroah-Hartman 823bccfc40 remove "struct subsystem" as it is no longer needed
We need to work on cleaning up the relationship between kobjects, ksets and
ktypes.  The removal of 'struct subsystem' is the first step of this,
especially as it is not really needed at all.

Thanks to Kay for fixing the bugs in this patch.

Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-05-02 18:57:59 -07:00
Jens Axboe 07e4470805 Merge branch 'cfq' into for-linus 2007-04-30 09:09:27 +02:00
Jens Axboe 2a12dcd71a [PATCH] elevator: elv_list_lock does not need irq disabling
It's never grabbed from irq context, so just make it plain spin_lock().

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-04-30 09:08:17 +02:00
Jens Axboe 597bc485d6 cfq-iosched: speedup cic rb lookup
We often lookup the same queue many times in succession, so cache
the last looked up queue to avoid browsing the rbtree.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-04-30 09:01:23 +02:00
Jens Axboe 4e521c27ee ll_rw_blk: add io_context private pointer
To be used by as/cfq as they see fit.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-04-30 09:01:23 +02:00
Vasily Tarasov 91fac317a3 cfq-iosched: get rid of cfqq hash
cfq hash is no more necessary.  We always can get cfqq from io context.
cfq_get_io_context_noalloc() function is introduced, because we don't
want to allocate cic on merging and checking may_queue.  In order to
identify sync queue we've used hash key = CFQ_KEY_ASYNC. Since hash is
eliminated we need to use other criterion: sync flag for queue is added.
In all places where we dig in rb_tree we're in current context, so no
additional locking is required.

Advantages of this patch: no additional memory for hash, no seeking in
hash, code is cleaner. But it is necessary now to seek cic in per-ioc
rbtree, but it is faster:
- most processes work only with few devices
- most systems have only few block devices
- it is a rb-tree

Signed-off-by: Vasily Tarasov <vtaras@openvz.org>

Changes by me:

- Merge into CFQ devel branch
- Get rid of cfq_get_io_context_noalloc()
- Fix various bugs with dereferencing cic->cfqq[] with offset other
  than 0 or 1.
- Fix bug in cfqq setup, is_sync condition was reversed.
- Fix bug where only bio_sync() is used, we need to check for a READ too

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-04-30 09:01:23 +02:00
Jens Axboe cc19747977 cfq-iosched: tighten queue request overlap condition
For tagged devices, allow overlap of requests if the idle window
isn't enabled on the current active queue.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-04-30 09:01:23 +02:00
Jens Axboe 3ed9a2965c cfq-iosched: improve sync vs async workloads
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-04-30 09:01:23 +02:00
Jens Axboe 1be92f2fc7 cfq-iosched: never allow an async queue idling
We don't enable it by default, don't let it get enabled during
runtime.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-04-30 09:01:22 +02:00
Jens Axboe 20e493a8d0 cfq-iosched: get rid of ->dispatch_slice
We can track it fairly accurately locally, let the slice handling
take care of the rest.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-04-30 09:01:22 +02:00
Jens Axboe 6084cdda0e cfq-iosched: don't pass unused preemption variable around
We don't use it anymore in the slice expiry handling.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-04-30 09:01:22 +02:00
Jens Axboe edd75ffd92 cfq-iosched: get rid of ->cur_rr and ->cfq_list
It's only used for preemption now that the IDLE and RT queues also
use the rbtree. If we pass an 'add_front' variable to
cfq_service_tree_add(), we can set ->rb_key to 0 to force insertion
at the front of the tree.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-04-30 09:01:22 +02:00
Jens Axboe 67e6b49e39 cfq-iosched: slice offset should take ioprio into account
Use the max_slice-cur_slice as the multipler for the insertion offset.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-04-30 09:01:22 +02:00
Jens Axboe 498d3aa2b4 [PATCH] cfq-iosched: style cleanups and comments
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-04-30 09:01:22 +02:00
Jens Axboe 67060e3799 cfq-iosched: sort IDLE queues into the rbtree
Same treatment as the RT conversion, just put the sorted idle
branch at the end of the tree.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-04-30 09:01:22 +02:00
Jens Axboe 0c534e0a46 cfq-iosched: sort RT queues into the rbtree
Currently CFQ does a linked insert into the current list for RT
queues. We can just factor the class into the rb insertion,
and then we don't have to treat RT queues in a special way. It's
faster, too.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-04-30 09:01:22 +02:00
Jens Axboe cc09e2990f [PATCH] cfq-iosched: speed up rbtree handling
For cases where the rbtree is mainly used for sorting and min retrieval,
a nice speedup of the rbtree code is to maintain a cache of the leftmost
node in the tree.

Also spotted in the CFS CPU scheduler code.

Improved by Alan D. Brunelle <Alan.Brunelle@hp.com> by updating the
leftmost hint in cfq_rb_first() if it isn't set, instead of only
updating it on insert.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-04-30 09:01:21 +02:00
Jens Axboe d9e7620e60 cfq-iosched: rework the whole round-robin list concept
Drawing on some inspiration from the CFS CPU scheduler design, overhaul
the pending cfq_queue concept list management. Currently CFQ uses a
doubly linked list per priority level for sorting and service uses.
Kill those lists and maintain an rbtree of cfq_queue's, sorted by when
to service them.

This unfortunately means that the ionice levels aren't as strong
anymore, will work on improving those later. We only scale the slice
time now, not the number of times we service. This means that latency
is better (for all priority levels), but that the distinction between
the highest and lower levels aren't as big.

The diffstat speaks for itself.

 cfq-iosched.c |  363 +++++++++++++++++---------------------------------
 1 file changed, 125 insertions(+), 238 deletions(-)

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-04-30 09:01:21 +02:00
Jens Axboe 1afba0451c cfq-iosched: minor updates
- Move the queue_new flag clear to when the queue is selected
- Only select the non-first queue in cfq_get_best_queue(), if there's
  a substantial difference between the best and first.
- Get rid of ->busy_rr
- Only select a close cooperator, if the current queue is known to take
  a while to "think".

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-04-30 09:01:21 +02:00
Jens Axboe 6d048f5310 cfq-iosched: development update
- Implement logic for detecting cooperating processes, so we
  choose the best available queue whenever possible.

- Improve residual slice time accounting.

- Remove dead code: we no longer see async requests coming in on
  sync queues. That part was removed a long time ago. That means
  that we can also remove the difference between cfq_cfqq_sync()
  and cfq_cfqq_class_sync(), they are now indentical. And we can
  kill the on_dispatch array, just make it a counter.

- Allow a process to go into the current list, if it hasn't been
  serviced in this scheduler tick yet.

Possible future improvements including caching the cfqq lookup
in cfq_close_cooperator(), so we don't have to look it up twice.
cfq_get_best_queue() should just use that last decision instead
of doing it again.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-04-30 09:01:21 +02:00
Jens Axboe 1e3335de05 cfq-iosched: improve preemption for cooperating tasks
When testing the syslet async io approach, I discovered that CFQ
sometimes didn't perform as well as expected. cfq_should_preempt()
needs to better check for cooperating tasks, so fix that by allowing
preemption of an equal priority queue if the recently queued request
is as good a candidate for IO as the one we are currently waiting for.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-04-30 09:01:21 +02:00
Jens Axboe 5044eed488 cfq-iosched: fix alias + front merge bug
There's a really rare and obscure bug in CFQ, that causes a crash in
cfq_dispatch_insert() due to rq == NULL.  One example of the resulting
oops is seen here:

	http://lkml.org/lkml/2007/4/15/41

Neil correctly diagnosed the situation for how this can happen: if two
concurrent requests with the exact same sector number (due to direct IO
or aliasing between MD and the raw device access), the alias handling
will add the request to the sortlist, but next_rq remains NULL.

Read the more complete analysis at:

	http://lkml.org/lkml/2007/4/25/57

This looks like it requires md to trigger, even though it should
potentially be possible to due with O_DIRECT (at least if you edit the
kernel and doctor some of the unplug calls).

The fix is to move the ->next_rq update to when we add a request to the
rbtree. Then we remove the possibility for a request to exist in the
rbtree code, but not have ->next_rq correctly updated.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-04-25 08:41:48 -07:00
Jens Axboe a993800655 cfq-iosched: fix sequential write regression
We have a 10-15% performance regression for sequential writes on TCQ/NCQ
enabled drives in 2.6.21-rcX after the CFQ update went in.  It has been
reported by Valerie Clement <valerie.clement@bull.net> and the Intel
testing folks.  The regression is because of CFQ's now more aggressive
queue control, limiting the depth available to the device.

This patches fixes that regression by allowing a greater depth when only
one queue is busy.  It has been tested to not impact sync-vs-async
workloads too much - we still do a lot better than 2.6.20.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-04-20 22:56:29 -07:00
Alan Stern 44ec95425c [SCSI] sg: cap reserved_size values at max_sectors
This patch (as857) modifies the SG_GET_RESERVED_SIZE and
SG_SET_RESERVED_SIZE ioctls in the sg driver, capping the values at
the device's request_queue's max_sectors value.  This will permit
cdrecord to obtain a legal value for the maximum transfer length,
fixing Bugzilla #7026.

The patch also caps the initial reserved_size value.  There's no
reason to have a reserved buffer larger than max_sectors, since it
would be impossible to use the extra space.

The corresponding ioctls in the block layer are modified similarly,
and the initial value for the reserved_size is set as large as
possible.  This will effectively make it default to max_sectors.
Note that the actual value is meaningless anyway, since block devices
don't have a reserved buffer.

Finally, the BLKSECTGET ioctl is added to sg, so that there will be a
uniform way for users to determine the actual max_sectors value for
any raw SCSI transport.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Acked-by: Douglas Gilbert <dougg@torque.net>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
2007-04-17 18:09:56 -04:00
Andrew Morton 2363cc0264 [PATCH] remove protection of LANANA-reserved majors
Revert all this.  It can cause device-mapper to receive a different major from
earlier kernels and it turns out that the Amanda backup program (via GNU tar,
apparently) checks major numbers on files when performing incremental backups.

Which is a bit broken of Amanda (or tar), but this feature isn't important
enough to justify the churn.

Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-04-04 21:12:47 -07:00
Thibaut VARENE 1ffb96c587 make elv_register() output atomic
Booting 2.6.21-rc3-g45592145 I noticed the following on one of my
machines in the bootlog:

io scheduler noop registered<6>Time: jiffies clocksource has been installed.

io scheduler deadline registered (default)

Looking at block/elevator.c, it appears that elv_register() uses two
consecutive printks in a non-atomic way, leading to the above glitch. The
attached trivial patch fixes this issue, by using a single printk.

Signed-off-by: Thibaut VARENE <varenet@parisc-linux.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-03-27 08:53:04 +02:00
Vasily Tarasov f772b3d9ca block: blk_max_pfn is somtimes wrong
There is a small problem in handling page bounce.

At the moment blk_max_pfn equals max_pfn, which is in fact not maximum
possible _number_ of a page frame, but the _amount_ of page frames.  For
example for the 32bit x86 node with 4Gb RAM, max_pfn = 0x100000, but not
0xFFFF.

request_queue structure has a member q->bounce_pfn and queue needs bounce
pages for the pages _above_ this limit.  This routine is handled by
blk_queue_bounce(), where the following check is produced:

	if (q->bounce_pfn >= blk_max_pfn)
		return;

Assume, that a driver has set q->bounce_pfn to 0xFFFF, but blk_max_pfn
equals 0x10000.  In such situation the check above fails and for each bio
we always fall down for iterating over pages tied to the bio.

I want to notice, that for quite a big range of device drivers (ide, md,
...) such problem doesn't happen because they use BLK_BOUNCE_ANY for
bounce_pfn.  BLK_BOUNCE_ANY is defined as blk_max_pfn << PAGE_SHIFT, and
then the check above doesn't fail.  But for other drivers, which obtain
reuired value from drivers, it fails.  For example sata_nv uses
ATA_DMA_MASK or dev->dma_mask.

I propose to use (max_pfn - 1) for blk_max_pfn.  And the same for
blk_max_low_pfn.  The patch also cleanses some checks related with
bounce_pfn.

Signed-off-by: Vasily Tarasov <vtaras@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-03-27 08:52:47 +02:00
Peter Zijlstra 6d740cd5b1 [PATCH] lockdep: annotate BLKPG_DEL_PARTITION
>=============================================
>[ INFO: possible recursive locking detected ]
>2.6.19-1.2909.fc7 #1
>---------------------------------------------
>anaconda/587 is trying to acquire lock:
> (&bdev->bd_mutex){--..}, at: [<c05fb380>] mutex_lock+0x21/0x24
>
>but task is already holding lock:
> (&bdev->bd_mutex){--..}, at: [<c05fb380>] mutex_lock+0x21/0x24
>
>other info that might help us debug this:
>1 lock held by anaconda/587:
> #0:  (&bdev->bd_mutex){--..}, at: [<c05fb380>] mutex_lock+0x21/0x24
>
>stack backtrace:
> [<c0405812>] show_trace_log_lvl+0x1a/0x2f
> [<c0405db2>] show_trace+0x12/0x14
> [<c0405e36>] dump_stack+0x16/0x18
> [<c043bd84>] __lock_acquire+0x116/0xa09
> [<c043c960>] lock_acquire+0x56/0x6f
> [<c05fb1fa>] __mutex_lock_slowpath+0xe5/0x24a
> [<c05fb380>] mutex_lock+0x21/0x24
> [<c04d82fb>] blkdev_ioctl+0x600/0x76d
> [<c04946b1>] block_ioctl+0x1b/0x1f
> [<c047ed5a>] do_ioctl+0x22/0x68
> [<c047eff2>] vfs_ioctl+0x252/0x265
> [<c047f04e>] sys_ioctl+0x49/0x63
> [<c0404070>] syscall_call+0x7/0xb

Annotate BLKPG_DEL_PARTITION's bd_mutex locking and add a little comment
clarifying the bd_mutex locking, because I confused myself and initially
thought the lock order was wrong too.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-20 17:10:16 -08:00