From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx182.postini.com [74.125.245.182]) by kanga.kvack.org (Postfix) with SMTP id EB4396B0044 for ; Thu, 27 Sep 2012 11:45:26 -0400 (EDT) Message-ID: <5064748A.4020509@redhat.com> Date: Thu, 27 Sep 2012 11:45:14 -0400 From: Rik van Riel MIME-Version: 1.0 Subject: Re: [PATCH v4] KSM: numa awareness sysfs knob References: <1348448166-1995-1-git-send-email-pholasek@redhat.com> In-Reply-To: <1348448166-1995-1-git-send-email-pholasek@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Petr Holasek Cc: Hugh Dickins , Andrea Arcangeli , Andrew Morton , Chris Wright , Izik Eidus , David Rientjes , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Anton Arapov On 09/23/2012 08:56 PM, Petr Holasek wrote: > Introduces new sysfs boolean knob /sys/kernel/mm/ksm/merge_across_nodes > which control merging pages across different numa nodes. > When it is set to zero only pages from the same node are merged, > otherwise pages from all nodes can be merged together (default behavior). > > Typical use-case could be a lot of KVM guests on NUMA machine > and cpus from more distant nodes would have significant increase > of access latency to the merged ksm page. Sysfs knob was choosen > for higher variability when some users still prefers higher amount > of saved physical memory regardless of access latency. > > Every numa node has its own stable & unstable trees because of faster > searching and inserting. Changing of merge_nodes value is possible only > when there are not any ksm shared pages in system. > > I've tested this patch on numa machines with 2, 4 and 8 nodes and > measured speed of memory access inside of KVM guests with memory pinned > to one of nodes with this benchmark: Acked-by: Rik van Riel -- 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/ . Don't email: email@kvack.org