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From: Anthony Liguori <anthony-rdkfGonbjUSkNkDKm+mE6A@public.gmane.org>
To: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
Cc: Marcelo Tosatti <marcelo-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org>,
	kvm-devel
	<kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org>,
	virtualization-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org
Subject: Re: [PATCH] KVM simplified virtio balloon driver
Date: Sat, 19 Jan 2008 16:37:43 -0600	[thread overview]
Message-ID: <47927BB7.7060805@codemonkey.ws> (raw)
In-Reply-To: <4791A085.8060502__30665.5007684187$1200726687$gmane$org-atKUWr5tajBWk0Htik3J/w@public.gmane.org>

Avi Kivity wrote:
> Rusty Russell wrote:
>> After discussions with Anthony Liguori, it seems that the virtio
>> balloon can be made even simpler.  Here's my attempt.
>>
>> Since the balloon requires Guest cooperation anyway, there seems
>> little reason to force it to tell the Host when it wants to reuse a
>> page.  It can simply fault it in.
>>
>>   
> 
> Faulting is synchronous, while deflating is (or can be made) 
> asynchronous. If the host needs to do some work to get the memory, the 
> guest will be slowed down considerably.

Good point.  Basically, we have two page hinting operations which 
roughly correspond to madvise(MADV_DONTNEED) and madvise(MADV_WILLNEED).

Regards,

Anthony Liguori

> If we have explicit deflate, the host can call madvise(MADV_WILLNEED) or 
> actually touch the pages before the guest accesses them.
> 
> 


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  parent reply	other threads:[~2008-01-19 22:37 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20080114200357.GA18354@dmt>
     [not found] ` <200801151032.09495.rusty@rustcorp.com.au>
     [not found]   ` <20080115190102.GA27645@dmt>
2008-01-16 23:12     ` [PATCH] KVM virtio balloon driver Dor Laor
     [not found]       ` <1200525166.26281.103.camel-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org>
2008-01-17  1:45         ` [PATCH] KVM simplified " Rusty Russell
     [not found]           ` <200801171245.59510.rusty-8n+1lVoiYb80n/F98K4Iww@public.gmane.org>
2008-01-17  2:14             ` Anthony Liguori
     [not found]               ` <478EBA22.30301-rdkfGonbjUSkNkDKm+mE6A@public.gmane.org>
2008-01-17  3:29                 ` Rusty Russell
     [not found]                   ` <200801171429.32888.rusty-8n+1lVoiYb80n/F98K4Iww@public.gmane.org>
2008-01-17  4:01                     ` Anthony Liguori
     [not found]                       ` <478ED32A.1060803-rdkfGonbjUSkNkDKm+mE6A@public.gmane.org>
2008-01-17  5:59                         ` Rusty Russell
2008-01-19  7:05                         ` Avi Kivity
2008-01-17  9:32             ` Christian Borntraeger
     [not found]               ` <200801171032.26198.borntraeger-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org>
2008-01-17 10:25                 ` Martin Schwidefsky
2008-01-17 11:40                   ` Dor Laor
2008-01-17 13:56                     ` Anthony Liguori
     [not found]                       ` <478F5E85.9020009-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
2008-01-17 23:01                         ` Dor Laor
     [not found]                           ` <1200610891.26281.171.camel-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org>
2008-01-17 23:35                             ` Anthony Liguori
2008-01-19  7:02             ` Avi Kivity
     [not found]           ` <4791A085.8060502__30665.5007684187$1200726687$gmane$org@qumranet.com>
     [not found]             ` <4791A085.8060502__30665.5007684187$1200726687$gmane$org-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2008-01-19 22:37               ` Anthony Liguori [this message]
     [not found]                 ` <47927BB7.7060805-rdkfGonbjUSkNkDKm+mE6A@public.gmane.org>
2008-01-20  0:24                   ` Marcelo Tosatti
2008-01-20  0:40                     ` Anthony Liguori
     [not found]                       ` <47929884.2010908-rdkfGonbjUSkNkDKm+mE6A@public.gmane.org>
2008-01-24  1:58                         ` Rusty Russell

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