From: Paolo Bonzini <pbonzini@redhat.com>
To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: Dmitry Monakhov <dmonakhov@odin.com>,
qemu-block@nongnu.org, Stefan Hajnoczi <stefanha@redhat.com>,
"Denis V. Lunev" <den@odin.com>,
qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [Qemu-block] [PATCH v5 0/2] block: enforce minimal 4096 alignment in qemu_blockalign
Date: Thu, 14 May 2015 11:13:03 +0200 [thread overview]
Message-ID: <5554671F.3030901@redhat.com> (raw)
In-Reply-To: <20150513154342.GB24352@stefanha-thinkpad.redhat.com>
On 13/05/2015 17:43, Stefan Hajnoczi wrote:
> A 64 MB buffer was given in the pwrite() call.
>
> The first and the last 128-page write requests may have partial
> pages, but why should the rest not use fully aligned 1024 sector
> writes?
>
> Maybe the buffer is split by the max sectors per request before
> the alignment requirements are considered. It would be more
> efficient to first split off the unaligned parts.
Sounds like this could be it---then it's very similar to the issue
fixed by kernel commit c6e666345e1b (block: split discard into aligned
requests, 2012-08-02).
Paolo
prev parent reply other threads:[~2015-05-14 9:13 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-04 13:42 [Qemu-devel] [PATCH v5 0/2] block: enforce minimal 4096 alignment in qemu_blockalign Denis V. Lunev
2015-05-04 13:42 ` [Qemu-devel] [PATCH 1/2] block: minimal bounce buffer alignment Denis V. Lunev
2015-05-04 13:42 ` [Qemu-devel] [PATCH 2/2] block: align bounce buffers to page Denis V. Lunev
2015-05-11 14:54 ` [Qemu-devel] [Qemu-block] " Stefan Hajnoczi
2015-05-11 15:32 ` Eric Blake
2015-05-11 15:40 ` Denis V. Lunev
2015-05-11 15:08 ` [Qemu-devel] [Qemu-block] [PATCH v5 0/2] block: enforce minimal 4096 alignment in qemu_blockalign Stefan Hajnoczi
2015-05-11 16:07 ` Denis V. Lunev
2015-05-11 16:38 ` Denis V. Lunev
2015-05-11 16:47 ` Denis V. Lunev
2015-05-12 10:01 ` Stefan Hajnoczi
2015-05-12 10:19 ` Denis V. Lunev
2015-05-12 10:46 ` Paolo Bonzini
2015-05-13 15:43 ` Stefan Hajnoczi
2015-05-13 16:46 ` Denis V. Lunev
2015-05-29 16:43 ` [Qemu-devel] " Paolo Bonzini
2015-06-01 10:34 ` Dmitry Monakhov
2015-06-01 10:41 ` Paolo Bonzini
2015-06-01 11:16 ` Dmitry Monakhov
2015-06-01 11:26 ` Paolo Bonzini
2015-06-01 11:57 ` Dmitry Monakhov
2015-05-14 9:13 ` Paolo Bonzini [this message]
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