File 0018-linux-user-Run-multi-threaded-code-.patch of Package qemu

Overview Repositories Revisions Requests Users Attributes Meta

File 0018-linux-user-Run-multi-threaded-code-.patch of Package qemu (Revision e6260184b51c5f4d935af18c0916f4db)

Currently displaying revision e6260184b51c5f4d935af18c0916f4db , Show latest

From 56618c4d867be2c42a625591946ac5059b46d365 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 4823aa0..ff5ed06 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -4334,6 +4334,15 @@ 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);

Places

File 0018-linux-user-Run-multi-threaded-code-.patch of Package qemu (Revision e6260184b51c5f4d935af18c0916f4db)

Places