From: Rik van Riel <riel@redhat.com>
To: Petr Holasek <pholasek@redhat.com>
Cc: Hugh Dickins <hughd@google.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Chris Wright <chrisw@sous-sol.org>,
Izik Eidus <izik.eidus@ravellosystems.com>,
David Rientjes <rientjes@google.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Anton Arapov <anton@redhat.com>
Subject: Re: [PATCH v4] KSM: numa awareness sysfs knob
Date: Thu, 27 Sep 2012 11:45:14 -0400 [thread overview]
Message-ID: <5064748A.4020509@redhat.com> (raw)
In-Reply-To: <1348448166-1995-1-git-send-email-pholasek@redhat.com>
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 <riel@redhat.com>
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WARNING: multiple messages have this Message-ID (diff)
From: Rik van Riel <riel@redhat.com>
To: Petr Holasek <pholasek@redhat.com>
Cc: Hugh Dickins <hughd@google.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Chris Wright <chrisw@sous-sol.org>,
Izik Eidus <izik.eidus@ravellosystems.com>,
David Rientjes <rientjes@google.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Anton Arapov <anton@redhat.com>
Subject: Re: [PATCH v4] KSM: numa awareness sysfs knob
Date: Thu, 27 Sep 2012 11:45:14 -0400 [thread overview]
Message-ID: <5064748A.4020509@redhat.com> (raw)
In-Reply-To: <1348448166-1995-1-git-send-email-pholasek@redhat.com>
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 <riel@redhat.com>
next prev parent reply other threads:[~2012-09-27 15:45 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-24 0:56 [PATCH v4] KSM: numa awareness sysfs knob Petr Holasek
2012-09-24 0:56 ` Petr Holasek
2012-09-27 15:45 ` Rik van Riel [this message]
2012-09-27 15:45 ` Rik van Riel
2012-09-28 11:26 ` Andrea Arcangeli
2012-09-28 11:26 ` Andrea Arcangeli
2012-10-01 0:36 ` Hugh Dickins
2012-10-01 0:36 ` Hugh Dickins
2012-10-01 11:53 ` Andrea Arcangeli
2012-10-01 11:53 ` Andrea Arcangeli
2012-10-01 23:47 ` Hugh Dickins
2012-10-01 23:47 ` Hugh Dickins
2012-10-01 1:37 ` Hugh Dickins
2012-10-01 1:37 ` Hugh Dickins
2012-10-01 8:14 ` Hugh Dickins
2012-10-01 8:14 ` Hugh Dickins
2012-10-08 23:00 ` Petr Holasek
2012-10-08 23:00 ` Petr Holasek
2012-10-23 6:28 ` Ni zhan Chen
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