From 8b0b1db0133e4218a9b45c09e53793c039edebe1 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 16 Jun 2009 15:33:39 -0700 Subject: remove put_cpu_no_resched() put_cpu_no_resched() is an optimization of put_cpu() which unfortunately can cause high latencies. The nfs iostats code uses put_cpu_no_resched() in a code sequence where a reschedule request caused by an interrupt between the get_cpu() and the put_cpu_no_resched() can delay the reschedule for at least HZ. The other users of put_cpu_no_resched() optimize correctly in interrupt code, but there is no real harm in using the put_cpu() function which is an alias for preempt_enable(). The extra check of the preemmpt count is not as critical as the potential source of missing a reschedule. Debugged in the preempt-rt tree and verified in mainline. Impact: remove a high latency source [akpm@linux-foundation.org: build fix] Signed-off-by: Thomas Gleixner Acked-by: Ingo Molnar Cc: Tony Luck Cc: Trond Myklebust Cc: "J. Bruce Fields" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/smp.h | 1 - 1 file changed, 1 deletion(-) (limited to 'include') diff --git a/include/linux/smp.h b/include/linux/smp.h index a69db820eed..9e3d8af0920 100644 --- a/include/linux/smp.h +++ b/include/linux/smp.h @@ -177,7 +177,6 @@ static inline void init_call_single_data(void) #define get_cpu() ({ preempt_disable(); smp_processor_id(); }) #define put_cpu() preempt_enable() -#define put_cpu_no_resched() preempt_enable_no_resched() /* * Callback to arch code if there's nosmp or maxcpus=0 on the -- cgit v1.2.3