Messages in this thread | | | Date | Wed, 09 Nov 2011 01:31:07 +0530 | From | "Srivatsa S. Bhat" <> | Subject | Re: [PATCH] thp: reduce khugepaged freezing latency |
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On 11/08/2011 08:59 PM, Andrea Arcangeli wrote: > Lack of set_freezable_with_signal() prevented khugepaged to be waken > up (and prevented to sleep again) across the > schedule_timeout_interruptible() calls after freezing() becomes > true. The tight loop in khugepaged_alloc_hugepage() also missed one > try_to_freeze() call in case alloc_hugepage() would repeatedly fail in > turn preventing the loop to break and to reach the try_to_freeze() in > the khugepaged main loop. > > khugepaged would still freeze just fine by trying again the next > minute but it's better if it freezes immediately. > > Reported-by: Jiri Slaby <jslaby@suse.cz> > Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> > --- > mm/huge_memory.c | 3 ++- > 1 files changed, 2 insertions(+), 1 deletions(-) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index 4298aba..67311d1 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -2277,6 +2277,7 @@ static struct page *khugepaged_alloc_hugepage(void) > if (!hpage) { > count_vm_event(THP_COLLAPSE_ALLOC_FAILED); > khugepaged_alloc_sleep(); > + try_to_freeze(); > } else > count_vm_event(THP_COLLAPSE_ALLOC); > } while (unlikely(!hpage) && > @@ -2331,7 +2332,7 @@ static int khugepaged(void *none) > { > struct mm_slot *mm_slot; > > - set_freezable(); > + set_freezable_with_signal(); > set_user_nice(current, 19); > > /* serialize with start_khugepaged() */ >
Why do we need to use both set_freezable_with_signal() and an additional try_to_freeze()? Won't just using either one of them be good enough? Or am I missing something here?
Thanks, Srivatsa S. Bhat
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