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Re: [Qemu-devel] [PATCH v6 00/22] block: Asynchronous request cancellati
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH v6 00/22] block: Asynchronous request cancellation |
Date: |
Thu, 11 Sep 2014 09:45:56 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.0 |
Il 11/09/2014 07:41, Fam Zheng ha scritto:
> v6: Drop bdrv_em_aiocb_info.cancel in patch 5. (Paolo)
>
> v5: Fix IDE callback. (Paolo)
> Fix blkdebug. (Paolo)
> Drop the DMA fix which is independent of this series. (Paolo)
> Incorperate Yuan's patch on quorum_aio_cancel. (Benoît)
> Commit message wording fix. (Benoît)
> Rename qemu_aio_release to qemu_aio_unref. (Benoît)
>
> v4: Drop AIOCBInfo.cancel.
>
> This series adds a new block layer API:
>
> void bdrv_aio_cancel_async(BlockDriverAIOCB *acb);
>
> And use it to emulate bdrv_aio_cancel.
>
> The function is similar to bdrv_aio_cancel in that it cancels an AIO request,
> but different that it doesn't block until the request is completely cancelled
> or done.
>
> More importantly, the completion callback, BlockDriverAIOCB.cb, is guaranteed
> to be called, so that the cb can take care of resource releasing and status
> reporting to guest, etc.
>
> In the following work, scsi emulation code will be shifted to use the async
> cancelling.
>
> One major benefit would be that when guest tries to cancel a request, where
> the
> request cannot be cancelled easily, (due to throttled BlockDriverState, a lost
> connection, or a large request queue), we don't need to block the whole vm
> with
> a busy loop, which is how bdrv_aio_cancel is implemented now.
>
> A test case that is easy to reproduce is, throttle a scsi-disk to a very low
> limit, for example 50 bps, then stress the guest block device with dd or fio.
>
> Currently, the vm will quickly hang when it loses patience and send a tmf
> command to cancel the request, at which point we will busy wait in
> bdrv_aio_cancel, until the request is slowly spit out from throttled_reqs.
>
> Later, we will change scsi device code to make this asynchronous, on top of
> bdrv_aio_cancel_async.
>
> Fam
>
>
> Fam Zheng (21):
> ide/ahci: Check for -ECANCELED in aio callbacks
> block: Add refcnt in BlockDriverAIOCB
> block: Add bdrv_aio_cancel_async
> block: Drop bdrv_em_co_aiocb_info.cancel
> block: Drop bdrv_em_aiocb_info.cancel
> thread-pool: Convert thread_pool_aiocb_info.cancel to cancel_async
> linux-aio: Convert laio_aiocb_info.cancel to .cancel_async
> dma: Convert dma_aiocb_info.cancel to .cancel_async
> iscsi: Convert iscsi_aiocb_info.cancel to .cancel_async
> archipelago: Drop archipelago_aiocb_info.cancel
> blkdebug: Drop blkdebug_aiocb_info.cancel
> blkverify: Drop blkverify_aiocb_info.cancel
> curl: Drop curl_aiocb_info.cancel
> qed: Drop qed_aiocb_info.cancel
> quorum: Convert quorum_aiocb_info.cancel to .cancel_async
> rbd: Drop rbd_aiocb_info.cancel
> sheepdog: Convert sd_aiocb_info.cancel to .cancel_async
> win32-aio: Drop win32_aiocb_info.cancel
> ide: Convert trim_aiocb_info.cancel to .cancel_async
> block: Drop AIOCBInfo.cancel
> block: Rename qemu_aio_release -> qemu_aio_unref
>
> Liu Yuan (1):
> quorum: fix quorum_aio_cancel()
>
> block.c | 72
> ++++++++++++++++++++++++------------------------
> block/archipelago.c | 19 ++-----------
> block/blkdebug.c | 17 ++----------
> block/blkverify.c | 21 +-------------
> block/curl.c | 16 ++++-------
> block/iscsi.c | 23 ++++------------
> block/linux-aio.c | 34 +++++++----------------
> block/qed.c | 23 +---------------
> block/quorum.c | 11 ++++----
> block/rbd.c | 25 ++---------------
> block/sheepdog.c | 54 ++++++++++++++++--------------------
> block/win32-aio.c | 18 ++----------
> dma-helpers.c | 20 +++-----------
> hw/ide/ahci.c | 3 ++
> hw/ide/core.c | 26 +++++++++++------
> include/block/aio.h | 7 +++--
> include/block/block.h | 1 +
> tests/test-thread-pool.c | 34 +++++++++++++++++------
> thread-pool.c | 36 +++++++++++-------------
> 19 files changed, 167 insertions(+), 293 deletions(-)
>
Reviewed-by: Paolo Bonzini <address@hidden>
... and nice diffstat too! :)
Paolo
- [Qemu-devel] [PATCH v6 13/22] curl: Drop curl_aiocb_info.cancel, (continued)
- [Qemu-devel] [PATCH v6 13/22] curl: Drop curl_aiocb_info.cancel, Fam Zheng, 2014/09/11
- [Qemu-devel] [PATCH v6 14/22] qed: Drop qed_aiocb_info.cancel, Fam Zheng, 2014/09/11
- [Qemu-devel] [PATCH v6 15/22] quorum: fix quorum_aio_cancel(), Fam Zheng, 2014/09/11
- [Qemu-devel] [PATCH v6 16/22] quorum: Convert quorum_aiocb_info.cancel to .cancel_async, Fam Zheng, 2014/09/11
- [Qemu-devel] [PATCH v6 17/22] rbd: Drop rbd_aiocb_info.cancel, Fam Zheng, 2014/09/11
- [Qemu-devel] [PATCH v6 18/22] sheepdog: Convert sd_aiocb_info.cancel to .cancel_async, Fam Zheng, 2014/09/11
- [Qemu-devel] [PATCH v6 19/22] win32-aio: Drop win32_aiocb_info.cancel, Fam Zheng, 2014/09/11
- [Qemu-devel] [PATCH v6 20/22] ide: Convert trim_aiocb_info.cancel to .cancel_async, Fam Zheng, 2014/09/11
- [Qemu-devel] [PATCH v6 21/22] block: Drop AIOCBInfo.cancel, Fam Zheng, 2014/09/11
- [Qemu-devel] [PATCH v6 22/22] block: Rename qemu_aio_release -> qemu_aio_unref, Fam Zheng, 2014/09/11
- Re: [Qemu-devel] [PATCH v6 00/22] block: Asynchronous request cancellation,
Paolo Bonzini <=
- Re: [Qemu-devel] [PATCH v6 00/22] block: Asynchronous request cancellation, Stefan Hajnoczi, 2014/09/15