From: Jakub Kicinski <kuba@kernel.org>
To: Allison Henderson <allison.henderson@oracle.com>
Cc: "netdev@vger.kernel.org" <netdev@vger.kernel.org>
Subject: Re: [PATCH 1/6] net/rds: Avoid queuing superfluous send and recv work
Date: Wed, 26 Mar 2025 09:42:45 -0700 [thread overview]
Message-ID: <20250326094245.094cef0d@kernel.org> (raw)
In-Reply-To: <3b02c34d2a15b4529b384ab91b27e5be0f941130.camel@oracle.com>
On Wed, 12 Mar 2025 07:50:11 +0000 Allison Henderson wrote:
> Thread A: Thread B:
> ----------------------------------- -----------------------------------
> Calls rds_sendmsg()
> Calls rds_send_xmit()
> Calls rds_cond_queue_send_work()
> Calls rds_send_worker()
> calls rds_clear_queued_send_work_bit()
> clears RDS_SEND_WORK_QUEUED in cp->cp_flags
> checks RDS_SEND_WORK_QUEUED in cp->cp_flags
But if the two threads run in parallel what prevents this check
to happen fully before the previous line on the "Thread A" side?
Please take a look at netif_txq_try_stop() for an example of
a memory-barrier based algo.
> Queues work on on cp->cp_send_w
> Calls rds_send_xmit()
> Calls rds_cond_queue_send_work()
> skips queueing work on cp->cp_send_w
next prev parent reply other threads:[~2025-03-26 16:42 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-27 4:26 [PATCH 0/6] RDS bug fix collection allison.henderson
2025-02-27 4:26 ` [PATCH 1/6] net/rds: Avoid queuing superfluous send and recv work allison.henderson
2025-03-01 0:19 ` Jakub Kicinski
2025-03-05 0:38 ` Allison Henderson
2025-03-05 0:44 ` Jakub Kicinski
2025-03-06 16:41 ` Allison Henderson
2025-03-06 18:18 ` Jakub Kicinski
2025-03-07 20:28 ` Allison Henderson
2025-03-08 2:53 ` Jakub Kicinski
2025-03-12 7:50 ` Allison Henderson
2025-03-26 16:42 ` Jakub Kicinski [this message]
2025-04-02 1:34 ` Allison Henderson
2025-04-02 16:18 ` Jakub Kicinski
2025-04-03 1:27 ` Allison Henderson
2025-02-27 4:26 ` [PATCH 2/6] net/rds: Re-factor and avoid superfluous queuing of reconnect work allison.henderson
2025-02-27 4:26 ` [PATCH 3/6] net/rds: RDS/TCP does not initiate a connection allison.henderson
2025-02-27 4:26 ` [PATCH 4/6] net/rds: No shortcut out of RDS_CONN_ERROR allison.henderson
2025-03-01 0:19 ` Jakub Kicinski
2025-03-05 0:38 ` Allison Henderson
2025-02-27 4:26 ` [PATCH 5/6] net/rds: rds_tcp_accept_one ought to not discard messages allison.henderson
2025-03-01 0:21 ` Jakub Kicinski
2025-03-06 16:41 ` Allison Henderson
2025-03-01 23:22 ` kernel test robot
2025-03-05 0:43 ` Allison Henderson
2025-03-04 10:28 ` Dan Carpenter
2025-03-05 0:39 ` Allison Henderson
2025-02-27 4:26 ` [PATCH 6/6] net/rds: Encode cp_index in TCP source port allison.henderson
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