[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] poor domU VBD performance.
On Thu, Mar 31 2005, Kurt Garloff wrote: > Hi, > > On Thu, Mar 31, 2005 at 09:33:12AM -0500, Philip R Auld wrote: > > This effects merging though, right? I don't think the the front > > end has done any merging. > > The noop elevator does front and back merging. > My understanding is that it's used in the frontend driver. > > Otherwise, unplugging on every block would indeed be quite bad ... Not necessarily - either your io rate is not fast enough to sustain a substantial queue depth, in that case you get plugging on basically every io anyways. If on the other hand the io rate is high enough to maintain a queue depth of > 1, then the plugging will never take place because the queue never empties. So all in all, I don't think the temporary work-around will be such a bad idea. I would still rather implement the queue tracking though, it should not be more than a few lines of code. And Philip, I will get the bio_sync() change merged :-) -- Jens Axboe _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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