linux-kernel - Re: [PATCH] virtio-blk: make the queue depth the max supportable by the hypervisor

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20140315135723.GA10475@infradead.org>
Date:	Sat, 15 Mar 2014 06:57:23 -0700
From:	Christoph Hellwig <hch@...radead.org>
To:	Theodore Ts'o <tytso@....edu>
Cc:	Linux Kernel Developers List <linux-kernel@...r.kernel.org>,
	Venkatesh Srinivas <venkateshs@...gle.com>,
	Rusty Russell <rusty@...tcorp.com.au>,
	"Michael S. Tsirkin" <mst@...hat.com>,
	virtio-dev@...ts.oasis-open.org,
	virtualization@...ts.linux-foundation.org,
	Frank Swiderski <fes@...gle.com>
Subject: Re: [PATCH] virtio-blk: make the queue depth the max supportable by
 the hypervisor

On Fri, Mar 14, 2014 at 11:34:31PM -0400, Theodore Ts'o wrote:
> The current virtio block sets a queue depth of 64, which is
> insufficient for very fast devices.  It has been demonstrated that
> with a high IOPS device, using a queue depth of 256 can double the
> IOPS which can be sustained.
> 
> As suggested by Venkatash Srinivas, set the queue depth by default to
> be one half the the device's virtqueue, which is the maximum queue
> depth that can be supported by the channel to the host OS (each I/O
> request requires at least two VQ entries).

I don't think this should be a module parameter.  The default sizing
should be based of the parameters of the actual virtqueue, and if we
want to allow tuning it it should be by a sysfs attribute, preferable
using the same semantics as SCSI.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/