Messages in this thread | | | Date | Sun, 7 Sep 2014 20:47:45 +0200 | From | Christoph Hellwig <> | Subject | Re: [PATCH] virtio_blk: merge S/G list entries by default |
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On Sun, Sep 07, 2014 at 02:41:53PM +0300, Michael S. Tsirkin wrote: > > Signed-off-by: Christoph Hellwig <hch@lst.de> > > OK so this is an optimization patch right? > What kind of performance gain is observed with it?
None. I actually wrote it when the block layer had a bug when dm was used on top of the !merge case, and I decided to send it out as there had been no discussion about disabling this by default on the existing blk-mq drivers.
At least for my qemu/kvm setup it doesn't make a difference either way, although not doing the cheap merge doesn't like the right kind of optimization to me.
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