From bb2c2983421cc2b39cd7174f9bfdbb0376d5fcb9 Mon Sep 17 00:00:00 2001 From: Alexander Graf 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 --- linux-user/syscall.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/linux-user/syscall.c b/linux-user/syscall.c index 8abe4cd..72701d4 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -4599,6 +4599,15 @@ 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);