From: Paolo Bonzini <pbonzini@redhat.com>
To: Fam Zheng <famz@redhat.com>
Cc: stefanha@redhat.com, qemu-devel@nongnu.org, qemu-block@nongnu.org
Subject: Re: [Qemu-devel] [PATCH 06/16] block: add BDS field to count in-flight requests
Date: Wed, 9 Mar 2016 09:22:53 +0100 [thread overview]
Message-ID: <56DFDD5D.7010401@redhat.com> (raw)
In-Reply-To: <20160309080030.GA30583@ad.usersys.redhat.com>
On 09/03/2016 09:00, Fam Zheng wrote:
>> > On 09/03/2016 04:35, Fam Zheng wrote:
>>>>> > >> > enum BdrvTrackedRequestType {
>>>>> > >> > BDRV_TRACKED_READ,
>>>>> > >> > BDRV_TRACKED_WRITE,
>>>>> > >> > - BDRV_TRACKED_FLUSH,
>>>>> > >> > - BDRV_TRACKED_IOCTL,
>>>>> > >> > BDRV_TRACKED_DISCARD,
>>> > > Okay, so flush and ioctl are not needed, but why is discard different?
>> >
>> > Discard can modify the contents of the device, so I think it's safer to
>> > serialize it against RMW and copy-on-read operations.
> Okay, that makes sense, but ioctl like SG_IO can also modify content, no?
If you use SG_IO you shouldn't use RMW (because scsi_read_complete traps
READ CAPACITY and sets the host block size as the guest block size) or
copy-on-read (because raw has no backing file).
Besides, BDRV_TRACKED_IOCTL didn't include sector_num/nr_sectors
operations so it didn't provide serialization.
Paolo
next prev parent reply other threads:[~2016-03-09 8:23 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-16 17:56 [Qemu-devel] [PATCH 00/16] AioContext fine-grained locking, part 1 of 3, including bdrv_drain rewrite Paolo Bonzini
2016-02-16 17:56 ` [Qemu-devel] [PATCH 01/16] block: make bdrv_start_throttled_reqs return void Paolo Bonzini
2016-02-16 17:56 ` [Qemu-devel] [PATCH 02/16] block: move restarting of throttled reqs to block/throttle-groups.c Paolo Bonzini
2016-03-09 1:26 ` Fam Zheng
2016-03-09 7:37 ` Paolo Bonzini
2016-02-16 17:56 ` [Qemu-devel] [PATCH 03/16] block: introduce bdrv_no_throttling_begin/end Paolo Bonzini
2016-03-09 1:45 ` Fam Zheng
2016-03-09 7:40 ` Paolo Bonzini
2016-02-16 17:56 ` [Qemu-devel] [PATCH 04/16] block: plug whole tree at once, introduce bdrv_io_unplugged_begin/end Paolo Bonzini
2016-02-16 17:56 ` [Qemu-devel] [PATCH 05/16] mirror: use bottom half to re-enter coroutine Paolo Bonzini
2016-03-09 3:19 ` Fam Zheng
2016-03-09 7:41 ` Paolo Bonzini
2016-02-16 17:56 ` [Qemu-devel] [PATCH 06/16] block: add BDS field to count in-flight requests Paolo Bonzini
2016-03-09 3:35 ` Fam Zheng
2016-03-09 7:43 ` Paolo Bonzini
2016-03-09 8:00 ` Fam Zheng
2016-03-09 8:22 ` Paolo Bonzini [this message]
2016-03-09 8:33 ` Fam Zheng
2016-02-16 17:56 ` [Qemu-devel] [PATCH 07/16] block: change drain to look only at one child at a time Paolo Bonzini
2016-03-09 3:41 ` Fam Zheng
2016-03-09 7:49 ` Paolo Bonzini
2016-03-16 16:39 ` Stefan Hajnoczi
2016-03-16 17:41 ` Paolo Bonzini
2016-03-17 0:57 ` Fam Zheng
2016-02-16 17:56 ` [Qemu-devel] [PATCH 08/16] blockjob: introduce .drain callback for jobs Paolo Bonzini
2016-03-16 17:56 ` Stefan Hajnoczi
2016-02-16 17:56 ` [Qemu-devel] [PATCH 09/16] block: wait for all pending I/O when doing synchronous requests Paolo Bonzini
2016-03-09 8:13 ` Fam Zheng
2016-03-09 8:23 ` Paolo Bonzini
2016-03-16 18:04 ` Stefan Hajnoczi
2016-02-16 17:56 ` [Qemu-devel] [PATCH 10/16] nfs: replace aio_poll with bdrv_drain Paolo Bonzini
2016-02-16 17:56 ` [Qemu-devel] [PATCH 11/16] sheepdog: disable dataplane Paolo Bonzini
2016-02-16 17:56 ` [Qemu-devel] [PATCH 12/16] aio: introduce aio_context_in_iothread Paolo Bonzini
2016-02-16 17:56 ` [Qemu-devel] [PATCH 13/16] block: only call aio_poll from iothread Paolo Bonzini
2016-03-09 8:30 ` Fam Zheng
2016-03-09 8:55 ` Paolo Bonzini
2016-03-09 9:10 ` Paolo Bonzini
2016-03-09 9:27 ` Fam Zheng
2016-02-16 17:56 ` [Qemu-devel] [PATCH 14/16] iothread: release AioContext around aio_poll Paolo Bonzini
2016-02-16 17:56 ` [Qemu-devel] [PATCH 15/16] qemu-thread: introduce QemuRecMutex Paolo Bonzini
2016-02-16 17:56 ` [Qemu-devel] [PATCH 16/16] aio: convert from RFifoLock to QemuRecMutex Paolo Bonzini
2016-03-08 17:51 ` [Qemu-devel] [PATCH 00/16] AioContext fine-grained locking, part 1 of 3, including bdrv_drain rewrite Paolo Bonzini
2016-03-09 8:46 ` Fam Zheng
2016-03-16 18:18 ` Stefan Hajnoczi
2016-03-16 22:29 ` Paolo Bonzini
2016-03-17 13:44 ` [Qemu-devel] [Qemu-block] " Stefan Hajnoczi
2016-03-17 13:48 ` Paolo Bonzini
2016-03-18 15:49 ` Stefan Hajnoczi
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