From: Zhang, Yanmin Date: Tue, 9 Sep 2008 03:26:33 +0000 (+0800) Subject: sched: fix 2.6.27-rc5 couldn't boot on tulsa machine randomly X-Git-Tag: v2.6.27-rc7~10^2~1 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=baf25731e54d06eb13dc4eda78c6dc7da4ce84e8;p=pandora-kernel.git sched: fix 2.6.27-rc5 couldn't boot on tulsa machine randomly On my tulsa x86-64 machine, kernel 2.6.25-rc5 couldn't boot randomly. Basically, function __enable_runtime forgets to reset rt_rq->rt_throttled to 0. When every cpu is up, per-cpu migration_thread is created and it runs very fast, sometimes to mark the corresponding rt_rq->rt_throttled to 1 very quickly. After all cpus are up, with below calling chain: sched_init_smp => arch_init_sched_domains => build_sched_domains => ... => cpu_attach_domain => rq_attach_root => set_rq_online => ... => _enable_runtime _enable_runtime is called against every rt_rq again, so rt_rq->rt_time is reset to 0, but rt_rq->rt_throttled might be still 1. Later on function do_sched_rt_period_timer couldn't reset it, and all RT tasks couldn't be scheduled to run on that cpu. here is RT task migration_thread which is woken up when a task is migrated to another cpu. Below patch fixes it against 2.6.27-rc5. Signed-off-by: Zhang Yanmin Signed-off-by: Ingo Molnar --- Reading git-diff-tree failed