From: Artem Savkov <asavkov@redhat.com>
To: Thomas Gleixner <tglx@linutronix.de>,
Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Anna-Maria Behnsen <anna-maria@linutronix.de>,
"David S. Miller" <davem@davemloft.net>,
Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
David Ahern <dsahern@kernel.org>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
Artem Savkov <asavkov@redhat.com>
Subject: [PATCH v5 0/2] Upper bound kernel timers
Date: Thu, 5 May 2022 15:18:09 +0200 [thread overview]
Message-ID: <20220505131811.3744503-1-asavkov@redhat.com> (raw)
In-Reply-To: <87zgkwjtq2.ffs@tglx>
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.
[1] https://lore.kernel.org/all/20210302001054.4qgrvnkltvkgikzr@treble/T/#u
---
Changes in v5:
- The least intrusive and most straightforward approach. This avoids touching
any of existing code. The timeout supplied is always reduced by a known
timer wheel error margin of 12.5%.
- Commit message adjustments.
Changes in v4:
- Drop any attempts to be smart when calculating timer adjustment and always
substract LVL_GRAN so that base clock lag won't be such a problem. This
means that in some cases we will always be early, but all we want is not to
be late.
Changes in v3:
- A different approach: instead of introducing upper bound timers try to
account for timer wheen granularity on timer (re)arming step.
- Not sure whether moving lvl calculation into a separate function is worth
it.
- Had a hard time naming the upper_bount_timeout() function - any suggestions
welcome.
Changes in v2:
- TIMER_UPPER_BOUND flag description added as a comment in timer.h
- Code style fixes
- More elaborate commit message in timer commit
Artem Savkov (2):
timer: add a function to adjust timeouts to be upper bound
net: make tcp keepalive timer upper bound
include/linux/timer.h | 1 +
kernel/time/timer.c | 14 ++++++++++++++
net/ipv4/inet_connection_sock.c | 2 +-
3 files changed, 16 insertions(+), 1 deletion(-)
--
2.34.1
next prev parent reply other threads:[~2022-05-05 13:18 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 ` Artem Savkov [this message]
2022-05-05 13:18 ` [PATCH v5 " 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 ` [PATCH v3 0/2] Upper bound kernel timers David Laight
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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