From: Paolo Bonzini <pbonzini@redhat.com>
To: Asias He <asias@redhat.com>
Cc: kvm@vger.kernel.org, "Michael S. Tsirkin" <mst@redhat.com>,
linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org,
Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH V3 3/3] virtio-blk: Add bio-based IO path for virtio-blk
Date: Mon, 30 Jul 2012 09:31:06 +0200 [thread overview]
Message-ID: <5016383A.5090008@redhat.com> (raw)
In-Reply-To: <501610E0.8000504@redhat.com>
Il 30/07/2012 06:43, Asias He ha scritto:
>>
>
> Yes. Something like this:
>
> qemu -drive file=foo.img,cache=writeback/unsafe
>
> is not safe against power losses also?
cache=writeback and cache=none are safe, cache=unsafe isn't.
> I think we can add REQ_FLUSH & REQ_FUA support to bio path and that
> deserves another patch.
You only need to add REQ_FLUSH support. The virtio-blk protocol does
not support REQ_FUA, because there's no easy way to do it in userspace.
Paolo
WARNING: multiple messages have this Message-ID (diff)
From: Paolo Bonzini <pbonzini@redhat.com>
To: Asias He <asias@redhat.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org,
"Michael S. Tsirkin" <mst@redhat.com>,
Christoph Hellwig <hch@lst.de>,
Minchan Kim <minchan.kim@gmail.com>,
Rusty Russell <rusty@rustcorp.com.au>
Subject: Re: [PATCH V3 3/3] virtio-blk: Add bio-based IO path for virtio-blk
Date: Mon, 30 Jul 2012 09:31:06 +0200 [thread overview]
Message-ID: <5016383A.5090008@redhat.com> (raw)
In-Reply-To: <501610E0.8000504@redhat.com>
Il 30/07/2012 06:43, Asias He ha scritto:
>>
>
> Yes. Something like this:
>
> qemu -drive file=foo.img,cache=writeback/unsafe
>
> is not safe against power losses also?
cache=writeback and cache=none are safe, cache=unsafe isn't.
> I think we can add REQ_FLUSH & REQ_FUA support to bio path and that
> deserves another patch.
You only need to add REQ_FLUSH support. The virtio-blk protocol does
not support REQ_FUA, because there's no easy way to do it in userspace.
Paolo
next prev parent reply other threads:[~2012-07-30 7:31 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-13 8:38 [PATCH V3 0/3] Improve virtio-blk performance Asias He
2012-07-13 8:38 ` Asias He
2012-07-13 8:38 ` [PATCH V3 1/3] block: Introduce __blk_segment_map_sg() helper Asias He
2012-07-13 8:38 ` [PATCH V3 2/3] block: Add blk_bio_map_sg() helper Asias He
2012-07-13 8:38 ` Asias He
2012-07-13 8:38 ` [PATCH V3 3/3] virtio-blk: Add bio-based IO path for virtio-blk Asias He
2012-07-13 8:38 ` Asias He
2012-07-27 0:33 ` Rusty Russell
2012-07-27 0:33 ` Rusty Russell
2012-07-28 2:38 ` Asias He
2012-07-28 2:38 ` Asias He
2012-07-28 6:42 ` Paolo Bonzini
2012-07-28 6:42 ` Paolo Bonzini
2012-07-30 4:43 ` Asias He
2012-07-30 4:43 ` Asias He
2012-07-30 7:31 ` Paolo Bonzini [this message]
2012-07-30 7:31 ` Paolo Bonzini
2012-07-30 13:44 ` Christoph Hellwig
2012-07-30 13:44 ` Christoph Hellwig
2012-08-02 6:28 ` Asias He
2012-08-02 6:28 ` Asias He
2012-07-30 13:43 ` Christoph Hellwig
2012-07-30 13:43 ` Christoph Hellwig
2012-07-31 8:43 ` Asias He
2012-07-31 8:43 ` Asias He
2012-07-29 12:59 ` Michael S. Tsirkin
2012-07-29 12:59 ` Michael S. Tsirkin
2012-07-30 0:26 ` Asias He
2012-07-30 0:26 ` Asias He
2012-07-27 6:29 ` Rusty Russell
2012-07-27 6:29 ` Rusty Russell
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