Re: [PATCH 0/6][RFC] virtio-blk: Change I/O path from request to BIO

[Stefan Hajnoczi]

On Wed, Dec 21, 2011 at 1:00 AM, Minchan Kim <minchan@xxxxxxxxxx> wrote:
> This patch is follow-up of Christohp Hellwig's work
> [RFC: ->make_request support for virtio-blk].
> http://thread.gmane.org/gmane.linux.kernel/1199763
>
> Quote from hch
> "This patchset allows the virtio-blk driver to support much higher IOP
> rates which can be driven out of modern PCI-e flash devices.  At this
> point it really is just a RFC due to various issues."

Basic question to make sure I understood this series: does this patch
bypass the guest I/O scheduler (but then you added custom batching
code into virtio_blk.c)?

If you're stumped by the performance perhaps compare blktraces of the
request approach vs the bio approach.  We're probably performing I/O
more CPU-efficiently but the I/O pattern itself is worse.

Stefan
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