From: Izik Eidus <izik.eidus@ravellosystems.com>
To: nai.xia@gmail.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 16:59:02 +0200 [thread overview]
Message-ID: <4D90A236.9030200@ravellosystems.com> (raw)
In-Reply-To: <201103282214.19345.nai.xia@gmail.com>
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)
WARNING: multiple messages have this Message-ID (diff)
From: Izik Eidus <izik.eidus@ravellosystems.com>
To: nai.xia@gmail.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 16:59:02 +0200 [thread overview]
Message-ID: <4D90A236.9030200@ravellosystems.com> (raw)
In-Reply-To: <201103282214.19345.nai.xia@gmail.com>
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)
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next prev parent reply other threads:[~2011-03-28 15:23 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 [this message]
2011-03-28 14:59 ` Izik Eidus
2011-03-28 15:29 ` Nai Xia
2011-03-28 15:29 ` Nai Xia
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