From: Paolo Bonzini <pbonzini@redhat.com>
To: Mark Wu <wudx05@gmail.com>
Cc: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [RFC PATCH 0/3] block: add support for 4k logical blocks
Date: Fri, 25 Nov 2011 09:27:43 +0100 [thread overview]
Message-ID: <4ECF517F.5050000@redhat.com> (raw)
In-Reply-To: <CAOfR6VEakwde7DrN_oBb3OOumqPsb50W6pLb3wAy5P3OPQN21Q@mail.gmail.com>
On 11/25/2011 08:26 AM, Mark Wu wrote:
> 1. This patch aims to add 4k logical support for qemu running on a host
> with 4k logical block size, right?
No, it adds support for 512b logical block sizes running on a host with
4k logical block size and cache=none. This is suboptimal as it requires
bounce buffers, but it can happen with migration and until libvirt
provides a knob for the guest's logical block size.
> For guest, we can use
> logical_block_size=4096 to achieve that even on a host with the
> logical_block_size of 512. Am I right?
Yes.
> 2. Can we just call bdrv_get_alignment in bdrv_open_common once and use
> the stored buffer_alignment for future usage instead of always
> calling bdrv_get_alignment in qemu_blockalign/qiov_is_aligned. What's
> the benefit of the dynamic way?
Yes, I think it's possible.
Paolo
next prev parent reply other threads:[~2011-11-25 8:27 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-23 16:51 [Qemu-devel] [RFC PATCH 0/3] block: add support for 4k logical blocks Paolo Bonzini
2011-11-23 16:51 ` [Qemu-devel] [RFC PATCH 1/3] block: add bdrv_get_alignment, use it Paolo Bonzini
2011-11-23 16:51 ` [Qemu-devel] [RFC PATCH 2/3] raw: implement raw_get_alignment Paolo Bonzini
2011-11-23 16:51 ` [Qemu-devel] [RFC PATCH 3/3] block: do not rely on the buffer alignment passed to the guest Paolo Bonzini
2011-11-25 7:26 ` [Qemu-devel] [RFC PATCH 0/3] block: add support for 4k logical blocks Mark Wu
2011-11-25 8:27 ` Paolo Bonzini [this message]
2011-11-25 11:13 ` Christoph Hellwig
2011-11-28 3:05 ` Mark Wu
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