4.0-stable review patch. If anyone has any objections, please let me know.
------------------ From: Mike Galbraith <[email protected]> commit f8e617f4582995f7c25ef25b4167213120ad122b upstream. To fully take advantage of MWAIT, apparently the CLFLUSH instruction needs another quirk on certain CPUs: proper barriers around it on certain machines. On a Q6600 SMP system, pipe-test scheduling performance, cross core, improves significantly: 3.8.13 487.2 KHz 1.000 3.13.0-master 415.5 KHz .852 3.13.0-master+ 415.2 KHz .852 + restore mwait_idle 3.13.0-master++ 488.5 KHz 1.002 + restore mwait_idle + IPI fix Since X86_BUG_CLFLUSH_MONITOR is already a quirk, don't create a separate quirk for the extra smp_mb()s. Signed-off-by: Mike Galbraith <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Ian Malone <[email protected]> Cc: Josh Boyer <[email protected]> Cc: Len Brown <[email protected]> Cc: Len Brown <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Mike Galbraith <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Link: http://lkml.kernel.org/r/[email protected] [ Ported to recent kernel, added comments about the quirk. ] Signed-off-by: Ingo Molnar <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- arch/x86/kernel/process.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -429,18 +429,22 @@ static int prefer_mwait_c1_over_halt(con static void mwait_idle(void) { - if (!need_resched()) { - if (this_cpu_has(X86_BUG_CLFLUSH_MONITOR)) + if (!current_set_polling_and_test()) { + if (this_cpu_has(X86_BUG_CLFLUSH_MONITOR)) { + smp_mb(); /* quirk */ clflush((void *)¤t_thread_info()->flags); + smp_mb(); /* quirk */ + } __monitor((void *)¤t_thread_info()->flags, 0, 0); - smp_mb(); if (!need_resched()) __sti_mwait(0, 0); else local_irq_enable(); - } else + } else { local_irq_enable(); + } + __current_clr_polling(); } void select_idle_routine(const struct cpuinfo_x86 *c) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
