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- linux-user: pin multi-threaded applications to a single host cpu

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OBS-URL: https://build.opensuse.org/package/show/Virtualization/qemu?expand=0&rev=92
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Alexander Graf 2012-07-10 18:44:07 +00:00 committed by Git OBS Bridge
parent 7102445230
commit 839eb8dd1b
3 changed files with 47 additions and 0 deletions
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40
0026-linux-user-Run-multi-threaded-code-.patch Normal file
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@ -0,0 +1,40 @@
From f85c851986d24df8700ffe447301786fe83819d0 Mon Sep 17 00:00:00 2001
From: Alexander Graf <agraf@suse.de>
Date: Tue, 10 Jul 2012 20:40:55 +0200
Subject: [PATCH] linux-user: Run multi-threaded code on a single core
Running multi-threaded code can easily expose some of the fundamental
breakages in QEMU's design. It's just not a well supported scenario.
So if we pin the whole process to a single host CPU, we guarantee that
we will never have concurrent memory access actually happen. We can still
get scheduled away at any time, so it's no complete guarantee, but apparently
it reduces the odds well enough to get my test cases to pass.
This gets Java 1.7 working for me again on my test box.
Signed-off-by: Alexander Graf <agraf@suse.de>
---
linux-user/syscall.c | 9 +++++++++
1 files changed, 9 insertions(+), 0 deletions(-)
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 46e964b..b0566cd 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -4298,6 +4298,15 @@ static int do_fork(CPUArchState *env, unsigned int flags, abi_ulong newsp,
if (nptl_flags & CLONE_SETTLS)
cpu_set_tls (new_env, newtls);
+ /* agraf: Pin ourselves to a single CPU when running multi-threaded.
+ This turned out to improve stability for me. */
+ {
+ cpu_set_t mask;
+ CPU_ZERO(&mask);
+ CPU_SET(0, &mask);
+ sched_setaffinity(0, sizeof(mask), &mask);
+ }
+
/* Grab a mutex so that thread setup appears atomic. */
pthread_mutex_lock(&clone_lock);

5
qemu.changes
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@ -1,3 +1,8 @@
-------------------------------------------------------------------
Tue Jul 10 18:43:31 UTC 2012 - agraf@suse.com
- linux-user: pin multi-threaded applications to a single host cpu
-------------------------------------------------------------------
Tue Jul 10 16:42:54 UTC 2012 - agraf@suse.com

2
qemu.spec
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@ -49,6 +49,7 @@ Patch0022: 0022-use-libexecdir-instead-of-ignoring-.patch
Patch0023: 0023-linux-user-Ignore-broken-loop-ioctl.patch
Patch0024: 0024-linux-user-fix-segmentation-fault-p.patch
Patch0025: 0025-linux-user-lock-tcg.patch.patch
Patch0026: 0026-linux-user-Run-multi-threaded-code-.patch
# this is to make lint happy
Source300: rpmlintrc
Source302: bridge.conf
@ -181,6 +182,7 @@ run cross-architecture builds.
%patch0023 -p1
%patch0024 -p1
%patch0025 -p1
%patch0026 -p1
%build
# build QEMU