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From: Rusty Russell <rusty@rustcorp.com.au>
To: Christoph Hellwig <hch@infradead.org>
Cc: Chris Wright <chrisw@sous-sol.org>, Jens Axboe <axboe@kernel.dk>,
        Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 5/5] virtio-blk: implement ->make_request
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Date: Thu, 06 Oct 2011 12:22:14 +1030
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On Wed, 05 Oct 2011 15:54:08 -0400, Christoph Hellwig <hch@infradead.org> wrote:
> Add an alternate I/O path that implements ->make_request for virtio-blk.
> This is required for high IOPs devices which get slowed down to 1/5th of
> the native speed by all the locking, memory allocation and other overhead
> in the request based I/O path.

Ouch.

I'd be tempted to just switch across to this, though I'd be interested
to see if the simple add_buf change I referred to before has some effect
by itself (I doubt it).

Also, though it's overkill I'd use standard list primitives rather than
open-coding a single linked list.

Thanks!
Rusty.