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From: Badari Pulavarty <pbadari@us.ibm.com>
To: Avi Kivity <avi@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>, kvm@vger.kernel.org
Subject: Re: [RFC] vhost-blk implementation
Date: Thu, 25 Mar 2010 07:36:45 -0700	[thread overview]
Message-ID: <4BAB74FD.2090009@us.ibm.com> (raw)
In-Reply-To: <4BAB1765.2070707@redhat.com>

Avi Kivity wrote:
> On 03/24/2010 10:22 PM, Badari Pulavarty wrote:
>>> Which caching mode is this?  I assume data=writeback, because otherwise
>>> you'd be doing synchronous I/O directly from the handler.
>>
>>
>> Yes. This is with default (writeback) cache model. As mentioned 
>> earlier, readhead is helping here
>> and most cases, data would be ready in the pagecache.
>
>
> btw, relying on readahead is problematic.  The guest already issues 
> readahead requests, and the host will issue readahead based on that 
> readahead, reading far into the future.
>
Sure. In my tests, I did O_DIRECT in the guest - so there is no 
readahead in the guest.

Thanks,
Badari


  reply	other threads:[~2010-03-25 14:36 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-03-23  1:00 [RFC] vhost-blk implementation Badari Pulavarty
2010-03-23  1:16 ` Anthony Liguori
2010-03-23  1:45   ` Badari Pulavarty
2010-03-23  2:00     ` Anthony Liguori
2010-03-23  2:50       ` Badari Pulavarty
2010-03-23 10:05         ` Avi Kivity
2010-03-23 14:48           ` Badari Pulavarty
2010-03-23 10:03 ` Avi Kivity
2010-03-23 14:55   ` Badari Pulavarty
2010-03-23 16:53     ` Avi Kivity
2010-03-24 20:05   ` Christoph Hellwig
2010-03-25  6:29     ` Avi Kivity
2010-03-25 15:48       ` Christoph Hellwig
2010-03-25 15:51         ` Avi Kivity
2010-03-25 15:00     ` Asdo
2010-04-05 19:59       ` Christoph Hellwig
2010-04-07  0:36         ` [RFC] vhost-blk implementation (v2) Badari Pulavarty
2010-03-23 10:09 ` [RFC] vhost-blk implementation Eran Rom
2010-03-24 20:04 ` Christoph Hellwig
2010-03-24 20:22   ` Badari Pulavarty
2010-03-25  7:57     ` Avi Kivity
2010-03-25 14:36       ` Badari Pulavarty [this message]
2010-03-25 15:57     ` Christoph Hellwig
2010-03-26 18:53       ` Eran Rom
2010-04-08 16:17         ` Stefan Hajnoczi
2010-04-05 19:23     ` Christoph Hellwig
2010-04-05 23:17       ` Badari Pulavarty
2010-03-24 20:27   ` Badari Pulavarty
2010-03-29 15:41   ` Badari Pulavarty
2010-03-29 18:20     ` Chris Wright
2010-03-29 20:37       ` Avi Kivity
2010-03-29 22:51         ` Badari Pulavarty
2010-03-29 23:56           ` Chris Wright
2010-03-30 12:43           ` Avi Kivity
2010-04-05 14:22     ` Stefan Hajnoczi
2010-04-06  2:27       ` Badari Pulavarty

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