From: David Laight <David.Laight@ACULAB.COM>
To: 'Artem Savkov' <asavkov@redhat.com>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
"Josh Poimboeuf" <jpoimboe@redhat.com>
Cc: "davem@davemloft.net" <davem@davemloft.net>,
"yoshfuji@linux-ipv6.org" <yoshfuji@linux-ipv6.org>,
Anna-Maria Gleixner <anna-maria@linutronix.de>,
"dsahern@kernel.org" <dsahern@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH v3 0/2] Upper bound kernel timers
Date: Wed, 30 Mar 2022 10:28:57 +0000 [thread overview]
Message-ID: <4975eaf09eae43dc964f879f343e5a2b@AcuMS.aculab.com> (raw)
In-Reply-To: <20220330082046.3512424-1-asavkov@redhat.com>
From: Artem Savkov
> Sent: 30 March 2022 09:21
>
> As previously discussed [1] we had a report of a regression in TCP keepalive
> timer where timers were up to 4 minutes late resulting in disconnects.
>
> This patchset tries to fix the problem by introducing upper bound kernel timers
> and making tcp keepalive timer use those.
Why not just fix the timer code to work properly (as it used to) so that the
timers expire within a short time of the requested interval.
This just requires that expiring 'long' timers get moved into the
higher precision 'wheels' (or whatever) before they actually expire.
The burden for this is minimal - it only affects long duration timers
that actually expire, and each timer only gets moved once for each
level of timer precision.
Perhaps you only need to move them two or three times in order to
get a reasonable accuracy.
No one is going to mind if a 5 minute timer is a second late.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2022-03-30 10:29 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-23 11:16 [PATCH 0/2] Upper bound mode for kernel timers Artem Savkov
2022-03-23 11:16 ` [PATCH 1/2] timer: introduce upper bound timers Artem Savkov
2022-03-23 18:40 ` Josh Poimboeuf
2022-03-24 9:14 ` [PATCH v2 0/2] Upper bound mode for kernel timers Artem Savkov
2022-03-24 9:14 ` [PATCH v2 1/2] timer: introduce upper bound timers Artem Savkov
2022-03-24 9:15 ` [PATCH v2 2/2] net: make tcp keepalive timer upper bound Artem Savkov
2022-03-24 12:28 ` [PATCH 1/2] timer: introduce upper bound timers Thomas Gleixner
2022-03-24 13:54 ` Thomas Gleixner
2022-03-26 21:13 ` Thomas Gleixner
2022-03-30 8:20 ` [PATCH v3 0/2] Upper bound kernel timers Artem Savkov
2022-03-30 8:20 ` [PATCH v3 1/2] timer: add a function to adjust timeouts to be upper bound Artem Savkov
2022-03-30 13:40 ` Anna-Maria Behnsen
2022-04-02 6:55 ` Artem Savkov
2022-04-05 15:33 ` Thomas Gleixner
2022-04-07 7:52 ` [PATCH v4 0/2] Upper bound kernel timers Artem Savkov
2022-04-07 7:52 ` [PATCH v4 1/2] timer: add a function to adjust timeouts to be upper bound Artem Savkov
2022-04-08 0:37 ` Thomas Gleixner
2022-04-08 5:39 ` Josh Poimboeuf
2022-04-12 13:42 ` Artem Savkov
2022-05-05 13:18 ` [PATCH v5 0/2] Upper bound kernel timers Artem Savkov
2022-05-05 13:18 ` [PATCH v5 1/2] timer: add a function to adjust timeouts to be upper bound Artem Savkov
2022-05-05 13:18 ` [PATCH v5 2/2] net: make tcp keepalive timer " Artem Savkov
2022-05-05 17:56 ` Josh Poimboeuf
2022-05-06 6:39 ` Artem Savkov
2022-05-06 16:24 ` Josh Poimboeuf
2022-07-26 22:42 ` [PATCH v5 0/2] Upper bound kernel timers Josh Poimboeuf
2022-04-07 7:52 ` [PATCH v4 2/2] net: make tcp keepalive timer upper bound Artem Savkov
[not found] ` <Yk1i3WrcVIICAiF0@samus.usersys.redhat.com>
2022-04-07 23:26 ` [PATCH v3 1/2] timer: add a function to adjust timeouts to be " Thomas Gleixner
2022-03-30 8:20 ` [PATCH v3 2/2] net: make tcp keepalive timer " Artem Savkov
2022-04-02 3:09 ` [net] 6ef3f95797: UBSAN:shift-out-of-bounds_in_kernel/time/timer.c kernel test robot
2022-04-02 7:11 ` Artem Savkov
2022-03-30 10:28 ` David Laight [this message]
2022-03-25 7:38 ` [timer] d41e0719d5: UBSAN:shift-out-of-bounds_in_lib/flex_proportions.c kernel test robot
2022-03-25 19:14 ` Thomas Gleixner
2022-03-23 11:16 ` [PATCH 2/2] net: make tcp keepalive timer upper bound Artem Savkov
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