From: Klaus Jensen <its@irrelevant.dk>
To: Kevin Wolf <kwolf@redhat.com>
Cc: qemu-block@nongnu.org, richard.henderson@linaro.org,
qemu-devel@nongnu.org
Subject: Re: [PULL 11/23] Revert "graph-lock: Disable locking for now"
Date: Mon, 10 Jul 2023 14:22:51 +0200 [thread overview]
Message-ID: <ZKv4G4A0l8EhMZoy@cormorant.local> (raw)
In-Reply-To: <20230628141526.293104-12-kwolf@redhat.com>
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On Jun 28 16:15, Kevin Wolf wrote:
> Now that bdrv_graph_wrlock() temporarily drops the AioContext lock that
> its caller holds, it can poll without causing deadlocks. We can now
> re-enable graph locking.
>
> This reverts commit ad128dff0bf4b6f971d05eb4335a627883a19c1d.
>
I'm seeing a pretty major performance regression on iothread-enabled
virtio-blk (and on some on-going iothread hw/nvme work) with this
applied. Something like ~300k iops prior to this vs ~200k after on my
set up. On master, virtio-blk is currently faster without an iothread
(~215k) than with (~200k).
I bisected the change in iops to this revert.
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next prev parent reply other threads:[~2023-07-10 12:23 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-28 14:15 [PULL 00/23] Block layer patches Kevin Wolf
2023-06-28 14:15 ` [PULL 01/23] iotests: Test active commit with iothread and background I/O Kevin Wolf
2023-06-28 14:15 ` [PULL 02/23] qdev-properties-system: Lock AioContext for blk_insert_bs() Kevin Wolf
2023-06-28 14:15 ` [PULL 03/23] test-block-iothread: " Kevin Wolf
2023-06-28 14:15 ` [PULL 04/23] block: Fix AioContext locking in bdrv_open_child() Kevin Wolf
2023-06-28 14:15 ` [PULL 05/23] block: Fix AioContext locking in bdrv_attach_child_common() Kevin Wolf
2023-06-28 14:15 ` [PULL 06/23] block: Fix AioContext locking in bdrv_reopen_parse_file_or_backing() Kevin Wolf
2023-06-28 14:15 ` [PULL 07/23] block: Fix AioContext locking in bdrv_open_inherit() Kevin Wolf
2023-06-28 14:15 ` [PULL 08/23] block: Fix AioContext locking in bdrv_open_backing_file() Kevin Wolf
2023-06-28 14:15 ` [PULL 09/23] blockjob: Fix AioContext locking in block_job_add_bdrv() Kevin Wolf
2023-06-28 14:15 ` [PULL 10/23] graph-lock: Unlock the AioContext while polling Kevin Wolf
2023-06-28 14:15 ` [PULL 11/23] Revert "graph-lock: Disable locking for now" Kevin Wolf
2023-07-10 12:22 ` Klaus Jensen [this message]
2023-07-10 12:40 ` Kevin Wolf
2023-07-10 14:03 ` Klaus Jensen
2023-06-28 14:15 ` [PULL 12/23] file-posix: remove incorrect coroutine_fn calls Kevin Wolf
2023-06-28 14:15 ` [PULL 13/23] qed: mark more functions as coroutine_fns and GRAPH_RDLOCK Kevin Wolf
2023-06-28 14:15 ` [PULL 14/23] vpc: " Kevin Wolf
2023-06-28 14:15 ` [PULL 15/23] bochs: " Kevin Wolf
2023-06-28 14:15 ` [PULL 16/23] block: mark another function as coroutine_fns and GRAPH_UNLOCKED Kevin Wolf
2023-06-28 14:15 ` [PULL 17/23] cloop: mark more functions as coroutine_fns and GRAPH_RDLOCK Kevin Wolf
2023-06-28 14:15 ` [PULL 18/23] dmg: " Kevin Wolf
2023-06-28 14:15 ` [PULL 19/23] vmdk: " Kevin Wolf
2023-06-28 14:15 ` [PULL 20/23] vhdx: " Kevin Wolf
2023-06-28 14:15 ` [PULL 21/23] qcow2: " Kevin Wolf
2023-06-28 14:15 ` [PULL 22/23] block: use bdrv_co_getlength in coroutine context Kevin Wolf
2023-06-28 14:15 ` [PULL 23/23] block: use bdrv_co_debug_event " Kevin Wolf
2023-06-29 6:11 ` [PULL 00/23] Block layer patches Richard Henderson
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