From: Mike Snitzer <snitzer@redhat.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: martin.petersen@oracle.com, mst@redhat.com,
rusty@rustcorp.com.au, qemu-devel@nongnu.org,
linux-kernel@vger.kernel.org,
Christoph Hellwig <hch@infradead.org>,
dm-devel@redhat.com, Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: virtio_blk: fix defaults for max_hw_sectors and max_segment_size
Date: Wed, 26 Nov 2014 18:00:55 -0500 [thread overview]
Message-ID: <20141126230055.GA32363@redhat.com> (raw)
In-Reply-To: <54764BD1.2070804@kernel.dk>
On Wed, Nov 26 2014 at 4:53pm -0500,
Jens Axboe <axboe@kernel.dk> wrote:
> On 11/26/2014 02:51 PM, Mike Snitzer wrote:
> >
> > But while you're here, I wouldn't mind getting your take on virtio-blk
> > setting max_hw_sectors to -1U.
> >
> > As I said in my original reply to mst: it only makes sense to set a
> > really high initial upper bound like that in a driver if that driver
> > goes on to stack an underlying device's limit.
>
> -1U should just work, IMHO, there's no reason we should need to cap it
> at some synthetic value. That said, it seems it should be one of
> those parameters that should be negotiated up and set appropriately.
I'm saying set it to the underlying device's value for max_hw_sectors --
not some synthetic value. So I think we're saying the same thing.
But it isn't immediately clear (to me) how that benefits virtio-blk
users (obviously they are getting by today). So until that is pinned
down I imagine nobody will care to extend the virtio-blk protocol to
allow stacking max_hw_sectors and max_sectors up.
prev parent reply other threads:[~2014-11-26 23:01 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-20 19:00 [PATCH] virtio_blk: fix defaults for max_hw_sectors and max_segment_size Mike Snitzer
2014-11-20 20:30 ` Michael S. Tsirkin
2014-11-20 21:15 ` Mike Snitzer
2014-11-26 5:58 ` Rusty Russell
2014-11-26 14:10 ` Mike Snitzer
2014-11-21 1:59 ` Mike Snitzer
2014-11-21 2:11 ` [PATCH v2] " Mike Snitzer
2014-11-21 9:54 ` [PATCH] " Christoph Hellwig
2014-11-21 15:49 ` Mike Snitzer
2014-11-26 19:48 ` Jens Axboe
2014-11-26 20:51 ` Mike Snitzer
2014-11-26 20:54 ` Jens Axboe
2014-11-26 21:51 ` Mike Snitzer
2014-11-26 21:53 ` Jens Axboe
2014-11-26 23:00 ` Mike Snitzer [this message]
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