From 5a24d8e40ae04bbc4cb20472e16c86f5b587d1cb 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 files changed, 9 insertions(+), 0 deletions(-) diff --git a/linux-user/syscall.c b/linux-user/syscall.c index 5113d22..7be6873 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -4432,6 +4432,15 @@ 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);