From: Max Reitz <mreitz@redhat.com>
To: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>,
"qemu-block@nongnu.org" <qemu-block@nongnu.org>
Cc: "fam@euphon.net" <fam@euphon.net>,
"kwolf@redhat.com" <kwolf@redhat.com>,
Denis Lunev <den@virtuozzo.com>,
"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
"armbru@redhat.com" <armbru@redhat.com>,
"stefanha@redhat.com" <stefanha@redhat.com>,
"jsnow@redhat.com" <jsnow@redhat.com>
Subject: Re: [Qemu-devel] [PATCH 4/8] block/backup: improve unallocated clusters skipping
Date: Fri, 9 Aug 2019 14:25:43 +0200 [thread overview]
Message-ID: <b3b788fc-cf2d-8fe4-df35-a3fd8f18995f@redhat.com> (raw)
In-Reply-To: <ba8ea007-06dd-03fb-9f9c-6e31a4764156@virtuozzo.com>
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On 09.08.19 09:50, Vladimir Sementsov-Ogievskiy wrote:
> 07.08.2019 21:01, Max Reitz wrote:
>> On 07.08.19 10:07, Vladimir Sementsov-Ogievskiy wrote:
>>> Limit block_status querying to request bounds on write notifier to
>>> avoid extra seeking.
>>
>> I don’t understand this reasoning. Checking whether something is
>> allocated for qcow2 should just mean an L2 cache lookup. Which we have
>> to do anyway when we try to copy data off the source.
>
> But for raw it's seeking.
(1) That’s a bug in block_status then, isn’t it?
file-posix cannot determine the allocation status, or rather, everything
is allocated. bdrv_co_block_status() should probably pass @want_zero on
to the driver’s implementation, and file-posix should just
unconditionally return DATA if it’s false.
(2) Why would you even use sync=top for raw nodes?
Max
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next prev parent reply other threads:[~2019-08-09 12:26 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-07 8:07 [Qemu-devel] [PATCH 0/8] backup improvements Vladimir Sementsov-Ogievskiy
2019-08-07 8:07 ` [Qemu-devel] [PATCH 1/8] block/backup: deal with zero detection Vladimir Sementsov-Ogievskiy
2019-08-07 8:07 ` [Qemu-devel] [PATCH 2/8] block/backup: refactor write_flags Vladimir Sementsov-Ogievskiy
2019-08-07 16:53 ` Max Reitz
2019-08-07 8:07 ` [Qemu-devel] [PATCH 3/8] block/io: handle alignment and max_transfer for copy_range Vladimir Sementsov-Ogievskiy
2019-08-07 17:28 ` Max Reitz
2019-08-09 7:50 ` Vladimir Sementsov-Ogievskiy
2019-08-07 8:07 ` [Qemu-devel] [PATCH 4/8] block/backup: improve unallocated clusters skipping Vladimir Sementsov-Ogievskiy
2019-08-07 18:01 ` Max Reitz
2019-08-09 7:50 ` Vladimir Sementsov-Ogievskiy
2019-08-09 9:12 ` Vladimir Sementsov-Ogievskiy
2019-08-09 10:25 ` Vladimir Sementsov-Ogievskiy
2019-08-09 10:10 ` Vladimir Sementsov-Ogievskiy
2019-08-09 12:25 ` Max Reitz [this message]
2019-08-09 12:47 ` Vladimir Sementsov-Ogievskiy
2019-08-09 12:53 ` Max Reitz
2019-08-07 8:07 ` [Qemu-devel] [PATCH 5/8] block/backup: fix backup_cow_with_offload for last cluster Vladimir Sementsov-Ogievskiy
2019-08-07 18:05 ` Max Reitz
2019-08-07 8:07 ` [Qemu-devel] [PATCH 6/8] block/backup: teach backup_cow_with_bounce_buffer to copy more at once Vladimir Sementsov-Ogievskiy
2019-08-07 18:25 ` Max Reitz
2019-08-07 8:07 ` [Qemu-devel] [PATCH 7/8] block/backup: merge duplicated logic into backup_do_cow Vladimir Sementsov-Ogievskiy
2019-08-07 18:37 ` Max Reitz
2019-08-07 8:07 ` [Qemu-devel] [PATCH 8/8] block/backup: backup_do_cow: use bdrv_dirty_bitmap_next_dirty_area Vladimir Sementsov-Ogievskiy
2019-08-07 18:46 ` Max Reitz
2019-08-09 7:54 ` Vladimir Sementsov-Ogievskiy
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