On Tue, May 31, 2011 at 02:55:28PM +0900, Minchan Kim wrote: > On Mon, May 30, 2011 at 10:59:04PM +0600, Rakib Mullick wrote: > > commit 468fd62ed9 (vmstats: add cond_resched() to refresh_cpu_vm_stats()) added cond_resched() in refresh_cpu_vm_stats. Purpose of that patch was to allow other threads to run in non-preemptive case. This patch, makes sure that cond_resched() gets called when !CONFIG_PREEMPT is set. In a preemptiable kernel we don't need to call cond_resched(). > > > > Signed-off-by: Rakib Mullick <rakib.mullick@xxxxxxxxx> > > Let me ask questions. > > 1. What's bad if we call cond_resched on CONFIG_PREEMPT? > Is refresh_cpu_vm_stats a hot path? > 2. There is no help to call explicit scheduling point on CONFIG_PREEMPTION? > > We used cond_resched without any ifdef/endif of CONFIG_PREEMPT. > In addtion, cond_resched includes __might_sleep which is debugging help for lock. > So I hope let it be if you have a big concern. typo ^^ unless -- Kind regards Minchan Kim -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>