linux-kernel - [PATCH v3 0/2] Upper bound kernel timers

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Message-Id: <20220330082046.3512424-1-asavkov@redhat.com>
Date:   Wed, 30 Mar 2022 10:20:44 +0200
From:   Artem Savkov <asavkov@...hat.com>
To:     netdev@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        asavkov@...hat.com, Josh Poimboeuf <jpoimboe@...hat.com>
Cc:     davem@...emloft.net, yoshfuji@...ux-ipv6.org,
        Anna-Maria Gleixner <anna-maria@...utronix.de>,
        dsahern@...nel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v3 0/2] Upper bound kernel timers

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 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             | 92 ++++++++++++++++++++++++++++-----
 net/ipv4/inet_connection_sock.c |  2 +-
 3 files changed, 81 insertions(+), 14 deletions(-)

-- 
2.34.1