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[Qemu-devel] Significant performance regression in qemu-system-mips.
From: |
Rob Landley |
Subject: |
[Qemu-devel] Significant performance regression in qemu-system-mips. |
Date: |
Wed, 24 Mar 2010 15:34:00 -0500 |
User-agent: |
KMail/1.11.2 (Linux/2.6.28-18-generic; KDE/4.2.2; x86_64; ; ) |
I have a native build under qemu that gets killed if it doesn't produce a line
of output for 60 seconds (hang detection enforced by the host monitoring
qemu's stdout with --nographic, not from within qemu).
In the most recent release version, it never came close to triggering on mips
with a 30 second timeout. In the current -git version (well, as of Thursday
anyway), it triggers frequently (about 90% of the time) even with a 60 second
timeout.
I bisected it to this:
commit 1828be316f6637d43dd4c4f5f32925b17fb8107f
Author: Paolo Bonzini <address@hidden>
Date: Wed Mar 10 11:38:41 2010 +0100
more alarm timer cleanup
The timer_alarm_pending variable is related to the alarm timer but not
placed in the struct. Also, in qemu_mod_timer the wrong flag was being
tested: the timer is rearmed in the alarm timer "bottom half", so the
right flag to test there is the "pending" flag.
Finally, I hoisted the NULL checks from alarm_has_dynticks to
host_alarm_handler.
Signed-off-by: Paolo Bonzini <address@hidden>
Signed-off-by: Anthony Liguori <address@hidden>
Reverting that patch fixed it (git show HEAD | patch -R -p1), by which I mean
three consecutive runs with 30 second timeout didn't trigger the hang
detection.
Unfortunately, I can't revert that patch in current origin/master because most
of the hunks fail...
Help?
Rob
--
Latency is more important than throughput. It's that simple. - Linus Torvalds
- [Qemu-devel] Significant performance regression in qemu-system-mips.,
Rob Landley <=
- Re: [Qemu-devel] Significant performance regression in qemu-system-mips., Artyom Tarasenko, 2010/03/25
- Re: [Qemu-devel] Significant performance regression in qemu-system-mips., Rob Landley, 2010/03/25
- Re: [Qemu-devel] Significant performance regression in qemu-system-mips., Rob Landley, 2010/03/26
- Re: [Qemu-devel] Significant performance regression in qemu-system-mips., Aurelien Jarno, 2010/03/26
- Re: [Qemu-devel] Significant performance regression in qemu-system-mips., Rob Landley, 2010/03/26
- Re: [Qemu-devel] Significant performance regression in qemu-system-mips., Aurelien Jarno, 2010/03/27
- Re: [Qemu-devel] Significant performance regression in qemu-system-mips., Rob Landley, 2010/03/27