From: Fabiano Rosas <farosas@suse.de>
To: peterx@redhat.com, qemu-devel@nongnu.org
Cc: Hao Xiang <hao.xiang@bytedance.com>,
Bryan Zhang <bryan.zhang@bytedance.com>,
peterx@redhat.com, Avihai Horon <avihaih@nvidia.com>,
Yuan Liu <yuan1.liu@intel.com>,
Prasad Pandit <ppandit@redhat.com>
Subject: Re: [PATCH v2 07/23] migration/multifd: Simplify locking in sender thread
Date: Fri, 02 Feb 2024 16:23:16 -0300 [thread overview]
Message-ID: <87r0huhdqz.fsf@suse.de> (raw)
In-Reply-To: <20240202102857.110210-8-peterx@redhat.com>
peterx@redhat.com writes:
> From: Peter Xu <peterx@redhat.com>
>
> The sender thread will yield the p->mutex before IO starts, trying to not
> block the requester thread. This may be unnecessary lock optimizations,
> because the requester can already read pending_job safely even without the
> lock, because the requester is currently the only one who can assign a
> task.
>
> Drop that lock complication on both sides:
>
> (1) in the sender thread, always take the mutex until job done
> (2) in the requester thread, check pending_job clear lockless
>
> Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
next prev parent reply other threads:[~2024-02-02 19:23 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-02 10:28 [PATCH v2 00/23] migration/multifd: Refactor ->send_prepare() and cleanups peterx
2024-02-02 10:28 ` [PATCH v2 01/23] migration/multifd: Drop stale comment for multifd zero copy peterx
2024-02-02 10:28 ` [PATCH v2 02/23] migration/multifd: multifd_send_kick_main() peterx
2024-02-02 10:28 ` [PATCH v2 03/23] migration/multifd: Drop MultiFDSendParams.quit, cleanup error paths peterx
2024-02-02 19:15 ` Fabiano Rosas
2024-02-02 10:28 ` [PATCH v2 04/23] migration/multifd: Postpone reset of MultiFDPages_t peterx
2024-02-02 10:28 ` [PATCH v2 05/23] migration/multifd: Drop MultiFDSendParams.normal[] array peterx
2024-02-09 0:06 ` [External] " Hao Xiang
2024-02-09 12:20 ` Fabiano Rosas
2024-02-14 2:16 ` Hao Xiang
2024-02-14 17:17 ` Fabiano Rosas
2024-02-02 10:28 ` [PATCH v2 06/23] migration/multifd: Separate SYNC request with normal jobs peterx
2024-02-02 19:21 ` Fabiano Rosas
2024-02-02 10:28 ` [PATCH v2 07/23] migration/multifd: Simplify locking in sender thread peterx
2024-02-02 19:23 ` Fabiano Rosas [this message]
2024-02-02 10:28 ` [PATCH v2 08/23] migration/multifd: Drop pages->num check " peterx
2024-02-02 10:28 ` [PATCH v2 09/23] migration/multifd: Rename p->num_packets and clean it up peterx
2024-02-02 10:28 ` [PATCH v2 10/23] migration/multifd: Move total_normal_pages accounting peterx
2024-02-02 10:28 ` [PATCH v2 11/23] migration/multifd: Move trace_multifd_send|recv() peterx
2024-02-02 10:28 ` [PATCH v2 12/23] migration/multifd: multifd_send_prepare_header() peterx
2024-02-02 10:28 ` [PATCH v2 13/23] migration/multifd: Move header prepare/fill into send_prepare() peterx
2024-02-02 19:26 ` Fabiano Rosas
2024-02-02 10:28 ` [PATCH v2 14/23] migration/multifd: Forbid spurious wakeups peterx
2024-02-02 10:28 ` [PATCH v2 15/23] migration/multifd: Split multifd_send_terminate_threads() peterx
2024-02-02 19:28 ` Fabiano Rosas
2024-02-02 10:28 ` [PATCH v2 16/23] migration/multifd: Change retval of multifd_queue_page() peterx
2024-02-02 19:29 ` Fabiano Rosas
2024-02-02 10:28 ` [PATCH v2 17/23] migration/multifd: Change retval of multifd_send_pages() peterx
2024-02-02 19:30 ` Fabiano Rosas
2024-02-02 10:28 ` [PATCH v2 18/23] migration/multifd: Rewrite multifd_queue_page() peterx
2024-02-02 20:47 ` Fabiano Rosas
2024-02-05 4:03 ` Peter Xu
2024-02-02 10:28 ` [PATCH v2 19/23] migration/multifd: Cleanup multifd_save_cleanup() peterx
2024-02-02 20:54 ` Fabiano Rosas
2024-02-05 4:25 ` Peter Xu
2024-02-02 10:28 ` [PATCH v2 20/23] migration/multifd: Cleanup multifd_load_cleanup() peterx
2024-02-02 20:55 ` Fabiano Rosas
2024-02-02 10:28 ` [PATCH v2 21/23] migration/multifd: Stick with send/recv on function names peterx
2024-02-02 21:03 ` Fabiano Rosas
2024-02-02 10:28 ` [PATCH v2 22/23] migration/multifd: Fix MultiFDSendParams.packet_num race peterx
2024-02-02 21:08 ` Fabiano Rosas
2024-02-05 4:05 ` Peter Xu
2024-02-02 10:28 ` [PATCH v2 23/23] migration/multifd: Optimize sender side to be lockless peterx
2024-02-02 21:34 ` Fabiano Rosas
2024-02-05 4:35 ` Peter Xu
2024-02-05 14:10 ` Fabiano Rosas
2024-02-05 14:24 ` Peter Xu
2024-02-05 17:59 ` Fabiano Rosas
2024-02-06 3:05 ` [PATCH v2 00/23] migration/multifd: Refactor ->send_prepare() and cleanups Peter Xu
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