File 0016-linux-user-Run-multi-threaded-code-.patch of Package qemu-linux-user

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File 0016-linux-user-Run-multi-threaded-code-.patch of Package qemu-linux-user (Revision 7d3d0db3578dc571957f3c85832f2f36)

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From 83f3a44fd54b4e1dd098e00e7d1ab70b2fe423ac 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 file changed, 9 insertions(+)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 758f747cc6..b36273de54 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -4704,6 +4704,15 @@ 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);

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File 0016-linux-user-Run-multi-threaded-code-.patch of Package qemu-linux-user (Revision 7d3d0db3578dc571957f3c85832f2f36)

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