From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757578Ab1I3Voa (ORCPT ); Fri, 30 Sep 2011 17:44:30 -0400 Received: from mx1.redhat.com ([209.132.183.28]:55014 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751083Ab1I3VoW (ORCPT ); Fri, 30 Sep 2011 17:44:22 -0400 Date: Fri, 30 Sep 2011 23:43:41 +0200 From: Johannes Weiner To: Rik van Riel Cc: Randy Dunlap , Satoru Moriya , linux-kernel@vger.kernel.org, linux-mm@kvack.org, lwoodman@redhat.com, Seiji Aguchi , akpm@linux-foundation.org, hughd@google.com, hannes@cmpxchg.org Subject: Re: [PATCH -v2 -mm] add extra free kbytes tunable Message-ID: <20110930214341.GB5096@redhat.com> References: <20110901105208.3849a8ff@annuminas.surriel.com> <20110901100650.6d884589.rdunlap@xenotime.net> <20110901152650.7a63cb8b@annuminas.surriel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110901152650.7a63cb8b@annuminas.surriel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 01, 2011 at 03:26:50PM -0400, Rik van Riel wrote: > Add a userspace visible knob to tell the VM to keep an extra amount > of memory free, by increasing the gap between each zone's min and > low watermarks. > > This is useful for realtime applications that call system > calls and have a bound on the number of allocations that happen > in any short time period. In this application, extra_free_kbytes > would be left at an amount equal to or larger than than the > maximum number of allocations that happen in any burst. > > It may also be useful to reduce the memory use of virtual > machines (temporarily?), in a way that does not cause memory > fragmentation like ballooning does. > > Signed-off-by: Rik van Riel Acked-by: Johannes Weiner Btw, I wonder if there should be a waking of the kswapds in setup_per_zone_wmarks() in general to make sure the new watermarks are met. But that applies to min_free_kbytes as well, so not a requirement for this patch. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with SMTP id 14E5B9000BD for ; Fri, 30 Sep 2011 17:44:22 -0400 (EDT) Date: Fri, 30 Sep 2011 23:43:41 +0200 From: Johannes Weiner Subject: Re: [PATCH -v2 -mm] add extra free kbytes tunable Message-ID: <20110930214341.GB5096@redhat.com> References: <20110901105208.3849a8ff@annuminas.surriel.com> <20110901100650.6d884589.rdunlap@xenotime.net> <20110901152650.7a63cb8b@annuminas.surriel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110901152650.7a63cb8b@annuminas.surriel.com> Sender: owner-linux-mm@kvack.org List-ID: To: Rik van Riel Cc: Randy Dunlap , Satoru Moriya , linux-kernel@vger.kernel.org, linux-mm@kvack.org, lwoodman@redhat.com, Seiji Aguchi , akpm@linux-foundation.org, hughd@google.com, hannes@cmpxchg.org On Thu, Sep 01, 2011 at 03:26:50PM -0400, Rik van Riel wrote: > Add a userspace visible knob to tell the VM to keep an extra amount > of memory free, by increasing the gap between each zone's min and > low watermarks. > > This is useful for realtime applications that call system > calls and have a bound on the number of allocations that happen > in any short time period. In this application, extra_free_kbytes > would be left at an amount equal to or larger than than the > maximum number of allocations that happen in any burst. > > It may also be useful to reduce the memory use of virtual > machines (temporarily?), in a way that does not cause memory > fragmentation like ballooning does. > > Signed-off-by: Rik van Riel Acked-by: Johannes Weiner Btw, I wonder if there should be a waking of the kswapds in setup_per_zone_wmarks() in general to make sure the new watermarks are met. But that applies to min_free_kbytes as well, so not a requirement for this patch. -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org