From: Izik Eidus <izike-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
To: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
Cc: andrea-atKUWr5tajBWk0Htik3J/w@public.gmane.org,
yaniv-atKUWr5tajBWk0Htik3J/w@public.gmane.org,
kvm-devel
<kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org>,
Chris Wright <chrisw-69jw2NvuJkxg9hUCZPvPmw@public.gmane.org>,
linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org
Subject: Re: [RFC][PATCH 0/5] Memory merging driver for Linux
Date: Thu, 24 Jan 2008 11:26:25 +0200 [thread overview]
Message-ID: <479859C1.1070301@qumranet.com> (raw)
In-Reply-To: <479824EA.7070603-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
Avi Kivity wrote:
> Chris Wright wrote:
>> * Izik Eidus (izike-atKUWr5tajBWk0Htik3J/w@public.gmane.org) wrote:
>>
>>> this module find this identical data (pages) and merge them into one
>>> single page
>>> this new page is write protected so in any case the guest will try
>>> to write to it do_wp_page will duplicate the page
>>>
>>
>> What happens if you've merged more pages than you can recover on write
>> faults?
>>
>
> You start to swap. Just like Linux when you start to write on
> fork()ed memory.
>
> A management application may start taking measures, like inflating
> balloons and migrating to other hosts, but swapping is needed as a
> last resort measure.
>
yes, write faults are getting into do_wp_page() that in turn create a
new anonymous/swappable page
so it is safe.
--
woof.
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WARNING: multiple messages have this Message-ID (diff)
From: Izik Eidus <izike@qumranet.com>
To: Avi Kivity <avi@qumranet.com>
Cc: Chris Wright <chrisw@sous-sol.org>,
kvm-devel <kvm-devel@lists.sourceforge.net>,
andrea@qumranet.com, dor.laor@qumranet.com, linux-mm@kvack.org,
yaniv@qumranet.com
Subject: Re: [kvm-devel] [RFC][PATCH 0/5] Memory merging driver for Linux
Date: Thu, 24 Jan 2008 11:26:25 +0200 [thread overview]
Message-ID: <479859C1.1070301@qumranet.com> (raw)
In-Reply-To: <479824EA.7070603@qumranet.com>
Avi Kivity wrote:
> Chris Wright wrote:
>> * Izik Eidus (izike@qumranet.com) wrote:
>>
>>> this module find this identical data (pages) and merge them into one
>>> single page
>>> this new page is write protected so in any case the guest will try
>>> to write to it do_wp_page will duplicate the page
>>>
>>
>> What happens if you've merged more pages than you can recover on write
>> faults?
>>
>
> You start to swap. Just like Linux when you start to write on
> fork()ed memory.
>
> A management application may start taking measures, like inflating
> balloons and migrating to other hosts, but swapping is needed as a
> last resort measure.
>
yes, write faults are getting into do_wp_page() that in turn create a
new anonymous/swappable page
so it is safe.
--
woof.
--
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next prev parent reply other threads:[~2008-01-24 9:26 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-01-21 16:05 [RFC][PATCH 0/5] Memory merging driver for Linux Izik Eidus
2008-01-21 16:05 ` Izik Eidus
[not found] ` <4794C2E1.8040607-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2008-01-23 17:05 ` Rik van Riel
2008-01-23 17:05 ` [kvm-devel] " Rik van Riel
[not found] ` <20080123120510.4014e382-Fuq27k0DHcCSkoNiqTzCLQ@public.gmane.org>
2008-01-23 17:54 ` Andrea Arcangeli
2008-01-23 17:54 ` [kvm-devel] " Andrea Arcangeli
[not found] ` <20080123175444.GH7141-lysg2Xt5kKMAvxtiuMwx3w@public.gmane.org>
2008-01-23 18:11 ` Izik Eidus
2008-01-23 18:11 ` [kvm-devel] " Izik Eidus
2008-01-24 5:38 ` Avi Kivity
2008-01-24 5:38 ` [kvm-devel] " Avi Kivity
2008-01-23 23:10 ` Chris Wright
2008-01-23 23:10 ` [kvm-devel] " Chris Wright
[not found] ` <20080123231037.GA3629-JyIX8gxvWYPr2PDY2+4mTGD2FQJk+8+b@public.gmane.org>
2008-01-24 5:40 ` Avi Kivity
2008-01-24 5:40 ` [kvm-devel] " Avi Kivity
[not found] ` <479824EA.7070603-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2008-01-24 9:26 ` Izik Eidus [this message]
2008-01-24 9:26 ` Izik Eidus
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