From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751780Ab1JKUXo (ORCPT ); Tue, 11 Oct 2011 16:23:44 -0400 Received: from usindpps06.hds.com ([207.126.252.19]:57958 "EHLO usindpps06.hds.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751262Ab1JKUXn convert rfc822-to-8bit (ORCPT ); Tue, 11 Oct 2011 16:23:43 -0400 From: Satoru Moriya To: Andrew Morton CC: David Rientjes , Rik van Riel , Randy Dunlap , Satoru Moriya , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "lwoodman@redhat.com" , Seiji Aguchi , "hughd@google.com" , "hannes@cmpxchg.org" Date: Tue, 11 Oct 2011 16:23:22 -0400 Subject: RE: [PATCH -v2 -mm] add extra free kbytes tunable Thread-Topic: [PATCH -v2 -mm] add extra free kbytes tunable Thread-Index: AcyIT5/cYvqtacUOT5CIAW74WZaPtwAA5Nyw Message-ID: <65795E11DBF1E645A09CEC7EAEE94B9CB516CBFE@USINDEVS02.corp.hds.com> References: <20110901105208.3849a8ff@annuminas.surriel.com> <20110901100650.6d884589.rdunlap@xenotime.net> <20110901152650.7a63cb8b@annuminas.surriel.com> <20111010153723.6397924f.akpm@linux-foundation.org> <65795E11DBF1E645A09CEC7EAEE94B9CB516CBC4@USINDEVS02.corp.hds.com> <20111011125419.2702b5dc.akpm@linux-foundation.org> In-Reply-To: <20111011125419.2702b5dc.akpm@linux-foundation.org> Accept-Language: ja-JP, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: ja-JP, en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 X-Proofpoint-Spam-Details: rule=outbound_policy_notspam policy=outbound_policy score=37 spamscore=37 ipscore=0 suspectscore=5 phishscore=0 bulkscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=6.0.2-1012030000 definitions=main-1110110246 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/11/2011 03:55 PM, Andrew Morton wrote: > On Tue, 11 Oct 2011 15:32:11 -0400 > Satoru Moriya wrote: > >> On 10/10/2011 06:37 PM, Andrew Morton wrote: >>> On Fri, 7 Oct 2011 20:08:19 -0700 (PDT) David Rientjes >>> wrote: >>> >>>> On Thu, 1 Sep 2011, Rik van Riel wrote: >> >> Actually page allocator decreases min watermark to 3/4 * min >> watermark for rt-task. But in our case some applications create a lot >> of processes and if all of them are rt-task, the amount of watermark >> bonus(1/4 * min watermark) is not enough. >> >> If we can tune the amount of bonus, it may be fine. But that is >> almost all same as extra free kbytes. > > This situation is detectable at runtime. If realtime tasks are being > stalled in the page allocator then start to increase the free-page > reserves. A little control system. Detecting at runtime is too late for some latency critical systems. At that system, we must avoid a stall before it happens. Also, if we increase the free-page reserves a.k.a min_free_kbytes, the possibility of direct reclaim on other workloads increases. I think it's a bad side effect. Thanks, Satoru From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail6.bemta7.messagelabs.com (mail6.bemta7.messagelabs.com [216.82.255.55]) by kanga.kvack.org (Postfix) with ESMTP id B2E926B002C for ; Tue, 11 Oct 2011 16:23:37 -0400 (EDT) From: Satoru Moriya Date: Tue, 11 Oct 2011 16:23:22 -0400 Subject: RE: [PATCH -v2 -mm] add extra free kbytes tunable Message-ID: <65795E11DBF1E645A09CEC7EAEE94B9CB516CBFE@USINDEVS02.corp.hds.com> References: <20110901105208.3849a8ff@annuminas.surriel.com> <20110901100650.6d884589.rdunlap@xenotime.net> <20110901152650.7a63cb8b@annuminas.surriel.com> <20111010153723.6397924f.akpm@linux-foundation.org> <65795E11DBF1E645A09CEC7EAEE94B9CB516CBC4@USINDEVS02.corp.hds.com> <20111011125419.2702b5dc.akpm@linux-foundation.org> In-Reply-To: <20111011125419.2702b5dc.akpm@linux-foundation.org> Content-Language: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: David Rientjes , Rik van Riel , Randy Dunlap , Satoru Moriya , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "lwoodman@redhat.com" , Seiji Aguchi , "hughd@google.com" , "hannes@cmpxchg.org" On 10/11/2011 03:55 PM, Andrew Morton wrote: > On Tue, 11 Oct 2011 15:32:11 -0400 > Satoru Moriya wrote: >=20 >> On 10/10/2011 06:37 PM, Andrew Morton wrote: >>> On Fri, 7 Oct 2011 20:08:19 -0700 (PDT) David Rientjes=20 >>> wrote: >>> >>>> On Thu, 1 Sep 2011, Rik van Riel wrote: >> >> Actually page allocator decreases min watermark to 3/4 * min=20 >> watermark for rt-task. But in our case some applications create a lot=20 >> of processes and if all of them are rt-task, the amount of watermark >> bonus(1/4 * min watermark) is not enough. >> >> If we can tune the amount of bonus, it may be fine. But that is=20 >> almost all same as extra free kbytes. >=20 > This situation is detectable at runtime. If realtime tasks are being=20 > stalled in the page allocator then start to increase the free-page=20 > reserves. A little control system. Detecting at runtime is too late for some latency critical systems. At that system, we must avoid a stall before it happens. Also, if we increase the free-page reserves a.k.a min_free_kbytes, the possibility of direct reclaim on other workloads increases. I think it's a bad side effect. Thanks, Satoru -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . 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