Messages in this thread | | | Date | Wed, 09 Nov 2011 18:15:38 +0530 | From | "Srivatsa S. Bhat" <> | Subject | Re: [PATCH] thp: reduce khugepaged freezing latency |
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On 11/09/2011 01:31 AM, Srivatsa S. Bhat wrote: > 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? >
Moreover, please note that Tejun Heo has sent patches to remove set_freezable_with_signal() altogether (he has even cleaned up the last existing user: usb_storage). So it wouldn't be good to start using it again, if it can be avoided.
http://thread.gmane.org/gmane.linux.kernel/1209416
Thanks, Srivatsa S. Bhat
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