From: Jakub Kicinski <kuba@kernel.org>
To: "Chia-Yu Chang (Nokia)" <chia-yu.chang@nokia-bell-labs.com>
Cc: "alok.a.tiwari@oracle.com" <alok.a.tiwari@oracle.com>,
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Subject: Re: [PATCH v20 net-next 1/6] sched: Struct definition and parsing of dualpi2 qdisc
Date: Mon, 30 Jun 2025 08:13:49 -0700 [thread overview]
Message-ID: <20250630081349.4c9d7976@kernel.org> (raw)
In-Reply-To: <PAXPR07MB79849FDC079A2ECB144D75D1A347A@PAXPR07MB7984.eurprd07.prod.outlook.com>
On Sun, 29 Jun 2025 22:49:24 +0000 Chia-Yu Chang (Nokia) wrote:
> > I don't get the reason for all these WRITE_ONCE()s.
> > You lock the qdisc to make modifications, right?
> > And the block under which I'm responding is performing two dependent writes, one to ->step_in_packets and the other to ->step_thresh a change which is definitely not atomic..
>
> Thanks again for other comments again, and I will take actions in the next version.
>
> As there is only one step marking in L-queue, so we still need two
> WRITE_ONCE even two attributes (one for threshold in packets and one
> in time) are used.
>
> When applying the step marking, we need to know either the
> computation is based on the sojourn time or queue length.
Let me ask again - why do you use WRITE_ONCE() at all if
the modification takes the qdisc lock? Which reader are
you afraid of racing with?
next prev parent reply other threads:[~2025-06-30 15:13 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-21 19:33 [PATCH v20 net-next 0/6] DUALPI2 patch chia-yu.chang
2025-06-21 19:33 ` [PATCH v20 net-next 1/6] sched: Struct definition and parsing of dualpi2 qdisc chia-yu.chang
2025-06-24 11:01 ` Paolo Abeni
2025-06-27 23:25 ` Jakub Kicinski
2025-06-29 22:49 ` Chia-Yu Chang (Nokia)
2025-06-30 15:13 ` Jakub Kicinski [this message]
2025-06-30 15:51 ` Chia-Yu Chang (Nokia)
2025-06-30 16:23 ` Jakub Kicinski
2025-06-30 17:04 ` Chia-Yu Chang (Nokia)
2025-06-30 23:43 ` Jakub Kicinski
2025-07-01 5:41 ` Chia-Yu Chang (Nokia)
2025-07-01 23:30 ` Jakub Kicinski
2025-06-21 19:33 ` [PATCH v20 net-next 2/6] sched: Dump configuration and statistics " chia-yu.chang
2025-06-21 19:33 ` [PATCH v20 net-next 3/6] sched: Add enqueue/dequeue " chia-yu.chang
2025-06-21 19:33 ` [PATCH v20 net-next 4/6] selftests/tc-testing: Fix warning and style check on tdc.sh chia-yu.chang
2025-06-21 19:33 ` [PATCH v20 net-next 5/6] selftests/tc-testing: Add selftests for qdisc DualPI2 chia-yu.chang
2025-06-21 19:33 ` [PATCH v20 net-next 6/6] Documentation: netlink: specs: tc: Add DualPI2 specification chia-yu.chang
2025-06-27 23:19 ` Jakub Kicinski
2025-06-29 22:32 ` Chia-Yu Chang (Nokia)
2025-06-30 15:12 ` Jakub Kicinski
2025-06-30 15:27 ` Chia-Yu Chang (Nokia)
2025-06-30 16:23 ` Jakub Kicinski
2025-06-24 11:08 ` [PATCH v20 net-next 0/6] DUALPI2 patch Paolo Abeni
2025-06-24 12:34 ` Ferenc Fejes
2025-06-24 13:53 ` Koen De Schepper (Nokia)
2025-06-25 10:10 ` Simon Horman
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