After commit b1bbfe7 (aio / timers: On timer modification, qemu_notify
or aio_notify, 2013-08-21) FreeBSD guests report a huge slowdown.
The problem shows up as soon as FreeBSD turns out its periodic (~1 ms)
tick, but the timers are only the trigger for a pre-existing problem.
Before the offending patch, setting a timer did a timer_settime system call.
After, setting the timer exits the event loop (which uses poll) and
reenters it with a new deadline. This does not cause any slowdown; the
difference is between one system call (timer_settime and a signal
delivery (SIGALRM) before the patch, and two system calls afterwards
(write to a pipe or eventfd + calling poll again when re-entering the
event loop).
Unfortunately, the exit/enter causes the main loop to grab the iothread
lock, which in turns kicks the VCPU thread out of execution. This
causes TCG to execute the next VCPU in its round-robin scheduling of
VCPUS. When the second VCPU is mostly unused, FreeBSD runs a "pause"
instruction in its idle loop which only burns cycles without any
progress. As soon as the timer tick expires, the first VCPU runs
the interrupt handler but very soon it sets it again---and QEMU
then goes back doing nothing in the second VCPU.
The fix is to make the pause instruction do "cpu_loop_exit".
Cc: Richard Henderson <rth@twiddle.net>
Reported-by: Luigi Rizzo <rizzo@iet.unipi.it>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Message-id: 1384948442-24217-1-git-send-email-pbonzini@redhat.com
Signed-off-by: Anthony Liguori <aliguori@amazon.com>
Move next_cpu from CPU_COMMON to CPUState.
Move first_cpu variable to qom/cpu.h.
gdbstub needs to use CPUState::env_ptr for now.
cpu_copy() no longer needs to save and restore cpu_next.
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
[AF: Rebased, simplified cpu_copy()]
Signed-off-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: liguang <lig.fnst@cn.fujitsu.com>
Reviewed-by: Andreas Färber <afaerber@suse.de>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
Signed-off-by: liguang <lig.fnst@cn.fujitsu.com>
Reviewed-by: Andreas Färber <afaerber@suse.de>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
Signed-off-by: liguang <lig.fnst@cn.fujitsu.com>
Reviewed-by: Andreas Färber <afaerber@suse.de>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
Signed-off-by: liguang <lig.fnst@cn.fujitsu.com>
Reviewed-by: Andreas Färber <afaerber@suse.de>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
Signed-off-by: liguang <lig.fnst@cn.fujitsu.com>
Reviewed-by: Andreas Färber <afaerber@suse.de>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
Signed-off-by: liguang <lig.fnst@cn.fujitsu.com>
Reviewed-by: Andreas Färber <afaerber@suse.de>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
This replaces the feature-bit fields on both X86CPU and x86_def_t
structs with an array.
With this, we will be able to simplify code that simply does the same
operation on all feature words (e.g. kvm_check_features_against_host(),
filter_features_for_kvm(), add_flagname_to_bitmaps(), CPU feature-bit
property lookup/registration, and the proposed "feature-words" property)
The following field replacements were made on X86CPU and x86_def_t:
(cpuid_)features -> features[FEAT_1_EDX]
(cpuid_)ext_features -> features[FEAT_1_ECX]
(cpuid_)ext2_features -> features[FEAT_8000_0001_EDX]
(cpuid_)ext3_features -> features[FEAT_8000_0001_ECX]
(cpuid_)ext4_features -> features[FEAT_C000_0001_EDX]
(cpuid_)kvm_features -> features[FEAT_KVM]
(cpuid_)svm_features -> features[FEAT_SVM]
(cpuid_)7_0_ebx_features -> features[FEAT_7_0_EBX]
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>
Both fields are used in VMState, thus need to be moved together.
Explicitly zero them on reset since they were located before
breakpoints.
Pass PowerPCCPU to kvmppc_handle_halt().
Signed-off-by: Andreas Färber <afaerber@suse.de>
Replace an if statement using magic numbers for breakpoint type with a
more explicit switch statement. This is to aid readability.
Change the return type and force_dr6_update argument type to bool.
While at it, fix Coding Style issues (missing braces).
Signed-off-by: liguang <lig.fnst@cn.fujitsu.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>
Implicit use of dr7 bit field is a little hard to understand,
so define constants for them and use them consistently.
Signed-off-by: liguang <lig.fnst@cn.fujitsu.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>
Note that target-alpha accesses this field from TCG, now using a
negative offset. Therefore the field is placed last in CPUState.
Pass PowerPCCPU to [kvm]ppc_fixup_cpu() to facilitate this change.
Move common parts of mips cpu_state_reset() to mips_cpu_reset().
Acked-by: Richard Henderson <rth@twiddle.net> (for alpha)
[AF: Rebased onto ppc CPU subclasses and openpic changes]
Signed-off-by: Andreas Färber <afaerber@suse.de>
Add an explicit CPUX86State parameter instead of relying on AREG0.
Remove temporary wrappers and switch to AREG0 free mode.
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
