From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932241Ab1KIQUh (ORCPT ); Wed, 9 Nov 2011 11:20:37 -0500 Received: from e23smtp07.au.ibm.com ([202.81.31.140]:59733 "EHLO e23smtp07.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752505Ab1KIQUg (ORCPT ); Wed, 9 Nov 2011 11:20:36 -0500 Message-ID: <4EBAA847.1060907@linux.vnet.ibm.com> Date: Wed, 09 Nov 2011 21:50:23 +0530 From: "Srivatsa S. Bhat" User-Agent: Mozilla/5.0 (X11; Linux i686; rv:7.0) Gecko/20110927 Thunderbird/7.0 MIME-Version: 1.0 To: Tejun Heo CC: Andrea Arcangeli , "Rafael J. Wysocki" , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Jiri Slaby , linux-mm@kvack.org, Andrew Morton Subject: Re: [PATCH] thp: reduce khugepaged freezing latency References: <4EB8E969.6010502@suse.cz> <1320766151-2619-1-git-send-email-aarcange@redhat.com> <1320766151-2619-2-git-send-email-aarcange@redhat.com> <4EB98A83.3040101@linux.vnet.ibm.com> <4EBA75F2.4080800@linux.vnet.ibm.com> <20111109155342.GA1260@google.com> In-Reply-To: <20111109155342.GA1260@google.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/09/2011 09:23 PM, Tejun Heo wrote: > Hello, Andrea, Srivatsa. > > On Wed, Nov 09, 2011 at 06:15:38PM +0530, Srivatsa S. Bhat wrote: >>>> 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); > > Oooh, please don't do that. It's already gone in the pm tree. It > would be best if wait_event_freezable_timeout() can be used > (ie. wakeup condition should be set somewhere) but, if not, something > like the following sould work. > > static void khugepaged_alloc_sleep(void) > { > DEFINE_WAIT(wait); > add_wait_queue(&khugepaged_wait, &wait); > try_to_freeze(); > schedule_timeout_interruptible( > msecs_to_jiffies( > khugepaged_alloc_sleep_millisecs)); > try_to_freeze(); > remove_wait_queue(&khugepaged_wait, &wait); > } > Right, Andrea this is what I meant. First of all we don't need both set_freezable_with_signal() _and_ an additional try_to_freeze(). And since we are anyway doing away with set_freezable_with_signal(), we can just use try_to_freeze() as Tejun suggested above. Thanks, Srivatsa S. Bhat