From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754739Ab1KIPxu (ORCPT ); Wed, 9 Nov 2011 10:53:50 -0500 Received: from mail-gy0-f174.google.com ([209.85.160.174]:51049 "EHLO mail-gy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751479Ab1KIPxt (ORCPT ); Wed, 9 Nov 2011 10:53:49 -0500 Date: Wed, 9 Nov 2011 07:53:42 -0800 From: Tejun Heo To: "Srivatsa S. Bhat" 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 Message-ID: <20111109155342.GA1260@google.com> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4EBA75F2.4080800@linux.vnet.ibm.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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); } Thanks. -- tejun