From 0f4f135a5ba1cfc6ff15f8bfd4a96d0a9738d943 Mon Sep 17 00:00:00 2001 From: davidxu Date: Fri, 10 Feb 2006 14:59:16 +0000 Subject: Test before modifying p_sflag to avoid unconditionally cache line ping-pong on SMP. --- sys/kern/subr_trap.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'sys/kern/subr_trap.c') diff --git a/sys/kern/subr_trap.c b/sys/kern/subr_trap.c index 686f613..c6af66b 100644 --- a/sys/kern/subr_trap.c +++ b/sys/kern/subr_trap.c @@ -182,9 +182,11 @@ ast(struct trapframe *framep) mtx_lock_spin(&sched_lock); flags = td->td_flags; sflag = p->p_sflag; - p->p_sflag &= ~(PS_ALRMPEND | PS_PROFPEND | PS_XCPU); + if (p->p_sflag & (PS_ALRMPEND | PS_PROFPEND | PS_XCPU)) + p->p_sflag &= ~(PS_ALRMPEND | PS_PROFPEND | PS_XCPU); #ifdef MAC - p->p_sflag &= ~PS_MACPEND; + if (p->p_sflag & PS_MACPEND) + p->p_sflag &= ~PS_MACPEND; #endif td->td_flags &= ~(TDF_ASTPENDING | TDF_NEEDSIGCHK | TDF_NEEDRESCHED | TDF_INTERRUPT); -- cgit v1.1