From: Nai Xia <nai.xia@gmail.com>
To: Izik Eidus <izik.eidus@ravellosystems.com>
Cc: "linux-kernel" <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Hugh Dickins <hughd@google.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Chris Wright <chrisw@sous-sol.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Rik van Riel <riel@redhat.com>, "linux-mm" <linux-mm@kvack.org>
Subject: Re: [PATCH 0/2] ksm: take dirty bit as reference to avoid volatile pages
Date: Mon, 28 Mar 2011 23:29:03 +0800 [thread overview]
Message-ID: <201103282329.04184.nai.xia@gmail.com> (raw)
In-Reply-To: <4D90A236.9030200@ravellosystems.com>
On Monday 28 March 2011 22:59:02 Izik Eidus wrote:
> On 03/28/2011 04:14 PM, Nai Xia wrote:
> > Currently, ksm uses page checksum to detect volatile pages. Izik Eidus
> > suggested that we could use pte dirty bit to optimize. This patch series
> > adds this new logic.
> >
>
> Hi,
>
> One small note:
> When kvm will use ksm on intel cpu with extended page tables support,
> the cpu won`t track
> dirty bit, therefore the calc_hash() logic should be used in such cases
> (untill intel will fadd this support in their cpus)...
>
> Moreover I think that even though that AMD nested page tables does
> update dirty bit, you still need
> to sync it with the host page table using mmu notifiers ?
>
> (Not that on regular application use case of ksm any of this should be
> an issue)
>
>
Hmm, I will consider these two issues in the next version. Thanks for
input!
Nai
WARNING: multiple messages have this Message-ID (diff)
From: Nai Xia <nai.xia@gmail.com>
To: Izik Eidus <izik.eidus@ravellosystems.com>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Hugh Dickins <hughd@google.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Chris Wright <chrisw@sous-sol.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Rik van Riel <riel@redhat.com>, linux-mm <linux-mm@kvack.org>
Subject: Re: [PATCH 0/2] ksm: take dirty bit as reference to avoid volatile pages
Date: Mon, 28 Mar 2011 23:29:03 +0800 [thread overview]
Message-ID: <201103282329.04184.nai.xia@gmail.com> (raw)
In-Reply-To: <4D90A236.9030200@ravellosystems.com>
On Monday 28 March 2011 22:59:02 Izik Eidus wrote:
> On 03/28/2011 04:14 PM, Nai Xia wrote:
> > Currently, ksm uses page checksum to detect volatile pages. Izik Eidus
> > suggested that we could use pte dirty bit to optimize. This patch series
> > adds this new logic.
> >
>
> Hi,
>
> One small note:
> When kvm will use ksm on intel cpu with extended page tables support,
> the cpu won`t track
> dirty bit, therefore the calc_hash() logic should be used in such cases
> (untill intel will fadd this support in their cpus)...
>
> Moreover I think that even though that AMD nested page tables does
> update dirty bit, you still need
> to sync it with the host page table using mmu notifiers ?
>
> (Not that on regular application use case of ksm any of this should be
> an issue)
>
>
Hmm, I will consider these two issues in the next version. Thanks for
input!
Nai
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next prev parent reply other threads:[~2011-03-28 15:29 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-28 14:14 [PATCH 0/2] ksm: take dirty bit as reference to avoid volatile pages Nai Xia
2011-03-28 14:14 ` Nai Xia
2011-03-28 14:59 ` Izik Eidus
2011-03-28 14:59 ` Izik Eidus
2011-03-28 15:29 ` Nai Xia [this message]
2011-03-28 15:29 ` Nai Xia
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