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From: Glauber Costa <glommer-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>
To: "cmcc.dylan" <dx10years-KN7UnAbNpbg@public.gmane.org>
Cc: "containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org"
	<containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org>,
	Kirill Korotaev <dev-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>
Subject: Re: the perfomance of lxc is not better than kvm+virtio
Date: Thu, 6 Sep 2012 18:39:54 +0400	[thread overview]
Message-ID: <5048B5BA.3070802@parallels.com> (raw)
In-Reply-To: <21d457be.9cee.1399be2b299.Coremail.dx10years-KN7UnAbNpbg@public.gmane.org>

On 09/06/2012 06:01 PM, cmcc.dylan wrote:
> 
> 
>> >2. 596 and even 700MB/sec makes me think you measure not real disk I/O, but memory (cache).
> i'm also think this is a results due to cache, for example page cache in the host os. Do you have some ideas bypassing memory cache?
> 
> 
Check your kvm command line. IIRC, KVM has a fully-cached mode of
operation. Writes to guest "disk" will not actually reach the disk for a
while. While this is nice, this is an unfair comparison from a benchmark
PoV, because of you are, of course, trading away a bit of your
data-safety. It is still safe against guest power-off, but not
necessarily against host power-off. Also, since there is no magic, this
can hurt you in very dense scenarios.

The "-drive" parameter will probably have a "cache" specifier, which is
what you are looking for.

  parent reply	other threads:[~2012-09-06 14:39 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-09-06  8:47 the perfomance of lxc is not better than kvm+virtio cmcc.dylan
     [not found] ` <369c0ce8.7437.1399ac363cf.Coremail.dx10years-KN7UnAbNpbg@public.gmane.org>
2012-09-06  9:27   ` Kirill Korotaev
     [not found]     ` <DF13143A-64A8-459C-B415-B3E661611C2A-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>
2012-09-06 14:01       ` cmcc.dylan
     [not found]         ` <21d457be.9cee.1399be2b299.Coremail.dx10years-KN7UnAbNpbg@public.gmane.org>
2012-09-06 14:39           ` Glauber Costa [this message]
2012-09-07  1:22           ` Zhu Yanhai

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