From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nivedita Singhvi Subject: Re: 2.4.29-xenU VBD performance (problem) Date: Thu, 17 Feb 2005 09:22:57 -0800 Message-ID: <4214D2F1.3040406@us.ibm.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit In-Reply-To: Sender: xen-devel-admin@lists.sourceforge.net Errors-To: xen-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , List-Archive: To: Ian Pratt Cc: =?ISO-8859-1?Q?Pasi_K=E4rkk=E4inen?= , xen-devel@lists.sourceforge.net, ian.pratt@cl.cam.ac.uk List-Id: xen-devel@lists.xenproject.org Ian Pratt wrote: >>But, under domU (2.4.29-xenU), using that same lvm-volume as >>VBD, I only get around >>10 - 12 MB/sec write performance measured in the same way. > > > That's very odd -- I see virtually no loss of throughput in a domU. > > However, 100MB isn't really enough to get a decent measure as its likely to all still be in memory -- sync doesn't do what you think. I usually do measurements using a transfer size of 10x the memory of the system. > > A couple of other things to try if you still experience poor peformance: > * use a 2.6 domU > * use a raw partition rather than LVM > > We do most of our testing using 2.6 for everything, so its possible there a weird 2.4 domU to 2.6 dom0 performance bug. Right. And to some extent, comparing 2.4 to 2.6 is a bit of an apples to oranges comparison. There are other differences in the kernel path - not just the virtual block driver coming out of domU. thanks, Nivedita ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click