Hi Andrew, On 06/27/2012 10:15 AM, Andrew Morton wrote: > On Wed, 27 Jun 2012 09:55:10 +0900 Minchan Kim <minchan@xxxxxxxxxx> wrote: > >> On 06/27/2012 06:37 AM, Andrew Morton wrote: >> >>> https://bugzilla.kernel.org/show_bug.cgi?id=43811 >>> >>> lru_add_drain_all() uses schedule_on_each_cpu(). But >>> schedule_on_each_cpu() hangs if a realtime thread is spinning, pinned >>> to a CPU. There's no intention to change the scheduler behaviour, so I >>> think we should remove schedule_on_each_cpu() from the kernel. >>> >>> The biggest user of schedule_on_each_cpu() is lru_add_drain_all(). >>> >>> Does anyone have any thoughts on how we can do this? The obvious >>> approach is to declare these: >>> >>> static DEFINE_PER_CPU(struct pagevec[NR_LRU_LISTS], lru_add_pvecs); >>> static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs); >>> static DEFINE_PER_CPU(struct pagevec, lru_deactivate_pvecs); >> >> >> One more >> static DEFINE_PER_CPU(struct pagevec, activate_page_pvecs); >> >>> >>> to be irq-safe and use on_each_cpu(). lru_rotate_pvecs is already >>> irq-safe and converting lru_add_pvecs and lru_deactivate_pvecs looks >>> pretty simple. >> >> >> Yes. Changing looks simple. >> I'm okay with lru_[activate_page|deactivate]_pvecs because it's not hot >> but lru_rotate_pvecs is hotter than others. > > I don't think any change is needed for lru_rotate_pvecs? Sorry for the typo lru_add_pvecs > >> Considering mlock and CPU pinning >> of realtime thread is very rare, it might be rather expensive solution. >> Unfortunately, I have no idea better than you suggested. :( >> >> And looking 8891d6da17, mlock's lru_add_drain_all isn't must. >> If it's really bother us, couldn't we remove it? > > "grep lru_add_drain_all mm/*.c". They're all problematic. > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@xxxxxxxxx. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a> > -- Kind regards, Minchan Kim -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>