From: Rik van Riel <riel@redhat.com>
To: Nai Xia <nai.xia@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>,
Izik Eidus <izik.eidus@ravellosystems.com>,
Avi Kivity <avi@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Hugh Dickins <hughd@google.com>,
Chris Wright <chrisw@sous-sol.org>, linux-mm <linux-mm@kvack.org>,
Johannes Weiner <hannes@cmpxchg.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
kvm <kvm@vger.kernel.org>
Subject: Re: [PATCH] mmu_notifier, kvm: Introduce dirty bit tracking in spte and mmu notifier to help KSM dirty bit tracking
Date: Wed, 22 Jun 2011 20:00:21 -0400 [thread overview]
Message-ID: <4E028215.90107@redhat.com> (raw)
In-Reply-To: <BANLkTinRYr9Vg==C-qyCaRmO7C_aQqBPzw@mail.gmail.com>
On 06/22/2011 07:37 PM, Nai Xia wrote:
> On 2MB pages, I'd like to remind you and Rik that ksmd currently splits
> huge pages before their sub pages gets really merged to stable tree.
Your proposal appears to add a condition that causes ksmd to skip
doing that, which can cause the system to start using swap instead
of sharing memory.
> So when there are many 2MB pages each having a 4kB subpage
> changed for all time, this is already a concern for ksmd to judge
> if it's worthwhile to split 2MB page and get its sub-pages merged.
> I think the policy for ksmd in a system should be "If you cannot do sth good,
> at least do nothing evil". So I really don't think we can satisfy _all_ people.
> Get a general method and give users one or two knobs to tune it when they
> are the corner cases. How do you think of my proposal ?
I think your proposal makes sense for 4kB pages, but the ksmd
policy for 2MB pages probably needs to be much more aggressive.
--
All rights reversed
WARNING: multiple messages have this Message-ID (diff)
From: Rik van Riel <riel@redhat.com>
To: Nai Xia <nai.xia@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>,
Izik Eidus <izik.eidus@ravellosystems.com>,
Avi Kivity <avi@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Hugh Dickins <hughd@google.com>,
Chris Wright <chrisw@sous-sol.org>, linux-mm <linux-mm@kvack.org>,
Johannes Weiner <hannes@cmpxchg.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
kvm <kvm@vger.kernel.org>
Subject: Re: [PATCH] mmu_notifier, kvm: Introduce dirty bit tracking in spte and mmu notifier to help KSM dirty bit tracking
Date: Wed, 22 Jun 2011 20:00:21 -0400 [thread overview]
Message-ID: <4E028215.90107@redhat.com> (raw)
In-Reply-To: <BANLkTinRYr9Vg==C-qyCaRmO7C_aQqBPzw@mail.gmail.com>
On 06/22/2011 07:37 PM, Nai Xia wrote:
> On 2MB pages, I'd like to remind you and Rik that ksmd currently splits
> huge pages before their sub pages gets really merged to stable tree.
Your proposal appears to add a condition that causes ksmd to skip
doing that, which can cause the system to start using swap instead
of sharing memory.
> So when there are many 2MB pages each having a 4kB subpage
> changed for all time, this is already a concern for ksmd to judge
> if it's worthwhile to split 2MB page and get its sub-pages merged.
> I think the policy for ksmd in a system should be "If you cannot do sth good,
> at least do nothing evil". So I really don't think we can satisfy _all_ people.
> Get a general method and give users one or two knobs to tune it when they
> are the corner cases. How do you think of my proposal ?
I think your proposal makes sense for 4kB pages, but the ksmd
policy for 2MB pages probably needs to be much more aggressive.
--
All rights reversed
--
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next prev parent reply other threads:[~2011-06-23 0:00 UTC|newest]
Thread overview: 96+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-21 12:55 [PATCH 0/2 V2] ksm: take dirty bit as reference to avoid volatile pages scanning Nai Xia
2011-06-21 12:55 ` Nai Xia
2011-06-21 13:26 ` [PATCH 1/2 " Nai Xia
2011-06-21 13:26 ` Nai Xia
2011-06-21 21:42 ` Chris Wright
2011-06-21 21:42 ` Chris Wright
2011-06-22 0:02 ` Nai Xia
2011-06-22 0:02 ` Nai Xia
2011-06-22 0:42 ` Chris Wright
2011-06-22 0:42 ` Chris Wright
2011-06-21 13:32 ` [PATCH] mmu_notifier, kvm: Introduce dirty bit tracking in spte and mmu notifier to help KSM dirty bit tracking Nai Xia
2011-06-21 13:32 ` Nai Xia
2011-06-22 0:21 ` Chris Wright
2011-06-22 0:21 ` Chris Wright
2011-06-22 4:43 ` Nai Xia
2011-06-22 4:43 ` Nai Xia
2011-06-22 6:15 ` Izik Eidus
2011-06-22 6:15 ` Izik Eidus
2011-06-22 6:38 ` Nai Xia
2011-06-22 6:38 ` Nai Xia
2011-06-22 15:46 ` Chris Wright
2011-06-22 15:46 ` Chris Wright
2011-06-22 10:43 ` Avi Kivity
2011-06-22 10:43 ` Avi Kivity
2011-06-22 11:05 ` Izik Eidus
2011-06-22 11:05 ` Izik Eidus
2011-06-22 11:10 ` Avi Kivity
2011-06-22 11:10 ` Avi Kivity
2011-06-22 11:19 ` Izik Eidus
2011-06-22 11:19 ` Izik Eidus
2011-06-22 11:24 ` Avi Kivity
2011-06-22 11:24 ` Avi Kivity
2011-06-22 11:28 ` Avi Kivity
2011-06-22 11:28 ` Avi Kivity
2011-06-22 11:31 ` Avi Kivity
2011-06-22 11:31 ` Avi Kivity
2011-06-22 11:33 ` Nai Xia
2011-06-22 11:33 ` Nai Xia
2011-06-22 11:39 ` Izik Eidus
2011-06-22 11:39 ` Izik Eidus
2011-06-22 15:39 ` Rik van Riel
2011-06-22 15:39 ` Rik van Riel
2011-06-22 16:55 ` Andrea Arcangeli
2011-06-22 16:55 ` Andrea Arcangeli
2011-06-22 23:37 ` Nai Xia
2011-06-22 23:37 ` Nai Xia
2011-06-22 23:59 ` Andrea Arcangeli
2011-06-22 23:59 ` Andrea Arcangeli
2011-06-23 0:31 ` Nai Xia
2011-06-23 0:31 ` Nai Xia
2011-06-23 0:44 ` Andrea Arcangeli
2011-06-23 0:44 ` Andrea Arcangeli
2011-06-23 1:36 ` Nai Xia
2011-06-23 1:36 ` Nai Xia
2011-06-23 0:00 ` Rik van Riel [this message]
2011-06-23 0:00 ` Rik van Riel
2011-06-23 0:42 ` Nai Xia
2011-06-23 0:42 ` Nai Xia
2011-06-22 23:13 ` Nai Xia
2011-06-22 23:13 ` Nai Xia
2011-06-22 23:25 ` Andrea Arcangeli
2011-06-22 23:25 ` Andrea Arcangeli
2011-06-23 1:30 ` Nai Xia
2011-06-23 1:30 ` Nai Xia
2011-06-22 23:28 ` Rik van Riel
2011-06-22 23:28 ` Rik van Riel
2011-06-23 0:52 ` Nai Xia
2011-06-23 0:52 ` Nai Xia
2011-06-22 11:24 ` Nai Xia
2011-06-22 15:03 ` Andrea Arcangeli
2011-06-22 15:03 ` Andrea Arcangeli
2011-06-22 15:19 ` Izik Eidus
2011-06-22 15:19 ` Izik Eidus
2011-06-22 23:19 ` Nai Xia
2011-06-22 23:19 ` Nai Xia
2011-06-22 23:44 ` Andrea Arcangeli
2011-06-22 23:44 ` Andrea Arcangeli
2011-06-23 0:14 ` Nai Xia
2011-06-23 0:14 ` Nai Xia
2011-06-22 23:42 ` Nai Xia
2011-06-22 23:42 ` Nai Xia
2011-06-21 13:36 ` [PATCH 2/2 V2] ksm: take dirty bit as reference to avoid volatile pages scanning Nai Xia
2011-06-21 13:36 ` Nai Xia
2011-06-21 22:38 ` Chris Wright
2011-06-21 22:38 ` Chris Wright
2011-06-22 0:04 ` Nai Xia
2011-06-22 0:04 ` Nai Xia
2011-06-22 0:35 ` Chris Wright
2011-06-22 0:35 ` Chris Wright
2011-06-22 4:47 ` Nai Xia
2011-06-22 4:47 ` Nai Xia
2011-06-22 10:55 ` Nai Xia
2011-06-22 10:55 ` Nai Xia
2011-06-22 0:46 ` [PATCH 0/2 " Chris Wright
2011-06-22 0:46 ` Chris Wright
2011-06-22 4:15 ` Nai Xia
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