linux-kernel - Re: [PATCH 2/5] virtio_blk: implement REQ

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: <4C6AB74E.7080909@kernel.org>
Date:	Tue, 17 Aug 2010 18:22:38 +0200
From:	Tejun Heo <tj@...nel.org>
To:	Christoph Hellwig <hch@....de>
CC:	jaxboe@...ionio.com, linux-fsdevel@...r.kernel.org,
	linux-scsi@...r.kernel.org, linux-ide@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-raid@...r.kernel.org,
	James.Bottomley@...e.de, tytso@....edu, chris.mason@...cle.com,
	swhiteho@...hat.com, konishi.ryusuke@....ntt.co.jp,
	dm-devel@...hat.com, vst@...b.net, jack@...e.cz,
	rwheeler@...hat.com, hare@...e.de, neilb@...e.de,
	rusty@...tcorp.com.au, mst@...hat.com
Subject: Re: [PATCH 2/5] virtio_blk: implement REQ_FLUSH/FUA support

Hello,

On 08/17/2010 03:23 PM, Christoph Hellwig wrote:
>> Hmmm... the underlying storage could be md/dm RAIDs in which case FUA
>> should be cheaper than FLUSH.
> 
> If someone ever wrote a virtio-blk backend that sits directly ontop
> of the Linux block layer that would be true.  Of the five known
> virtio-blk backends all operate on normal files using the Posix I/O
> APIs, or the Linux aio API (optionally in qemu) or in-kernel
> vfs_read/vfs_write (vhost-blk).

Right.

> Given how little testing lguest gets compared to qemu I really don't
> want a protocol addition for it unless it really buys us something.
> Once we're done with this barrier conversion I plan into benchmarking
> FUA and a pre-flush tag on the command for virtio in real life setups,
> and see if it actually buys us anything.

Hmmm... yeah, we can drop it.  Michael, what do you think?

Thanks.

-- 
tejun
--
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/