From: Eric Blake <eblake@redhat.com>
To: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
Cc: kwolf@redhat.com, Paolo Bonzini <pbonzini@redhat.com>,
aliguori@us.ibm.com, qemu-devel@nongnu.org, stefanha@gmail.com
Subject: Re: [Qemu-devel] [PATCH 4/6] libqblock internal used functions
Date: Tue, 04 Sep 2012 05:38:52 -0600 [thread overview]
Message-ID: <5045E84C.6030902@redhat.com> (raw)
In-Reply-To: <5045AA90.4050001@linux.vnet.ibm.com>
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On 09/04/2012 01:15 AM, Wenchao Xia wrote:
> 于 2012-9-3 23:18, Paolo Bonzini 写道:
>> Il 03/09/2012 16:28, Eric Blake ha scritto:
>>>>> +/* this file contains helper function used internally. */
>>>>> +#define SECTOR_SIZE (512)
>>> Hard-coding this feels wrong, in this day and age of disks with 4096
>>> sectors. Why isn't this a per-image property?
>>
>> In this day and age of disks with 4096 sectors, Linux does not provide a
>> way to query the required alignment for O_DIRECT...
>>
>> Paolo
>>
> in block.h:
> #define BDRV_SECTOR_BITS 9
> #define BDRV_SECTOR_SIZE (1ULL << BDRV_SECTOR_BITS)
> #define BDRV_SECTOR_MASK ~(BDRV_SECTOR_SIZE - 1)
> it seems block size is always 512 in qemu block layer, so I can
> ignore the 4096 case, do you think so?
Since qemu does not support it now, yes, you can ignore it for now. But
please make sure that you aren't hard-coding it into the API - that is,
make sure that the API can someday grow to support larger sector sizes
with minimal impact to library clients (that is, that new clients aware
of the new API can target larger sector size once qemu has been patched
to support larger sector size).
--
Eric Blake eblake@redhat.com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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next prev parent reply other threads:[~2012-09-04 11:39 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-03 9:18 [Qemu-devel] [PATCH 0/6] libqblock, qemu block layer library Wenchao Xia
2012-09-03 9:18 ` [Qemu-devel] [PATCH 1/6] libqblock APIs Wenchao Xia
2012-09-03 13:18 ` Paolo Bonzini
2012-09-04 3:15 ` Wenchao Xia
2012-09-04 6:50 ` Paolo Bonzini
2012-09-04 9:05 ` Wenchao Xia
2012-09-10 8:10 ` Wenchao Xia
2012-09-03 13:56 ` Eric Blake
2012-09-03 14:05 ` Paolo Bonzini
2012-09-04 7:05 ` Wenchao Xia
2012-09-04 7:29 ` Paolo Bonzini
2012-09-04 6:42 ` Wenchao Xia
2012-09-04 11:35 ` Eric Blake
2012-09-04 13:47 ` Paolo Bonzini
2012-09-03 19:22 ` Blue Swirl
2012-09-03 9:18 ` [Qemu-devel] [PATCH 2/6] libqblock public type defines Wenchao Xia
2012-09-03 13:13 ` Paolo Bonzini
2012-09-04 2:00 ` Wenchao Xia
2012-09-03 14:20 ` Eric Blake
2012-09-04 7:10 ` Wenchao Xia
2012-09-04 7:37 ` Paolo Bonzini
2012-09-03 19:31 ` Blue Swirl
2012-09-04 7:19 ` Wenchao Xia
2012-09-04 7:38 ` Paolo Bonzini
2012-09-04 19:22 ` Blue Swirl
2012-09-10 8:22 ` Wenchao Xia
2012-09-03 9:18 ` [Qemu-devel] [PATCH 3/6] libqblock error handling Wenchao Xia
2012-09-03 14:22 ` Eric Blake
2012-09-04 7:12 ` Wenchao Xia
2012-09-10 8:20 ` Wenchao Xia
2012-09-03 9:18 ` [Qemu-devel] [PATCH 4/6] libqblock internal used functions Wenchao Xia
2012-09-03 13:18 ` Paolo Bonzini
2012-09-04 3:19 ` Wenchao Xia
2012-09-03 14:28 ` Eric Blake
2012-09-03 15:18 ` Paolo Bonzini
2012-09-04 7:15 ` Wenchao Xia
2012-09-04 7:38 ` Paolo Bonzini
2012-09-04 11:38 ` Eric Blake [this message]
2012-09-04 13:49 ` Paolo Bonzini
2012-09-04 13:51 ` Kevin Wolf
2012-09-10 8:23 ` Wenchao Xia
2012-09-03 9:18 ` [Qemu-devel] [PATCH 5/6] libqblock test example Wenchao Xia
2012-09-03 19:27 ` Blue Swirl
2012-09-03 9:18 ` [Qemu-devel] [PATCH 6/6] libqblock building system Wenchao Xia
2012-09-03 13:10 ` [Qemu-devel] xbzrle migration cache size advise for high memory changes workload ? Alexandre DERUMIER
2012-09-04 14:05 ` Orit Wasserman
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