On Fri 09-06-17 15:38:44, David Rientjes wrote: > On Thu, 8 Jun 2017, Michal Hocko wrote: > > > I would just pull the cond_resched out of __collapse_huge_page_copy > > right after pte_unmap. But I am not really sure why this cond_resched is > > really needed because the changelog of the patch which adds is is quite > > terse on details. > > I'm not sure what could possibly be added to the changelog. We have > encountered need_resched warnings during the iteration. Well, the part the changelog is not really clear about is whether the HPAGE_PMD_NR loops itself is the source of the stall. This would be quite surprising because doing 512 iterations taking up to 20+s sounds way to much. So is it possible that we are missing a cond_resched somewhere up the __collapse_huge_page_copy call path? Or do we really do something stupidly expensive here? > We fix these > because need_resched warnings suppress future warnings of the same type > for issues that are more important. Sure thing. I do care about soft lockups as well. > I can fix the i386 issue but removing the cond_resched() entirely isn't > really suitable. I am not calling for a complete removal. I just do not yet see what is the source of the long processing of the the loop. -- Michal Hocko SUSE Labs -- 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>
