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. 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? -- 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>