From patchwork Wed Mar 30 08:20:44 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Artem Savkov X-Patchwork-Id: 12795567 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 01C79C4332F for ; Wed, 30 Mar 2022 08:21:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235034AbiC3IW6 (ORCPT ); Wed, 30 Mar 2022 04:22:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57682 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244272AbiC3IWr (ORCPT ); Wed, 30 Mar 2022 04:22:47 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 53BB331374 for ; Wed, 30 Mar 2022 01:21:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1648628461; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=IO9KTSJjuWPlQ5rED48189b51lrDyfed52txFxWKnsw=; b=SITZHVIHBxdHc6mukVt/Thvc11uu70CcnGHM403By5t92/rJI7oXNH8nOr1nSRbFC6DAZV AR2IDTPaSf/dUbTDWDUMBvbvNcry5s35Dgbgo0eYoBtMFdvVa7hBg7Mnthf6B2KMWvJHvG M+Bq3UIj60q+wI3S5vi3BtTnb+VKCxg= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-381-O-Hwf6t1Oky512CILG5EVQ-1; Wed, 30 Mar 2022 04:20:57 -0400 X-MC-Unique: O-Hwf6t1Oky512CILG5EVQ-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 5E0203C11C67; Wed, 30 Mar 2022 08:20:51 +0000 (UTC) Received: from shodan.usersys.redhat.com (unknown [10.43.17.22]) by smtp.corp.redhat.com (Postfix) with ESMTPS id BD97540CF8E4; Wed, 30 Mar 2022 08:20:49 +0000 (UTC) Received: by shodan.usersys.redhat.com (Postfix, from userid 1000) id A042D1C0162; Wed, 30 Mar 2022 10:20:46 +0200 (CEST) From: Artem Savkov To: netdev@vger.kernel.org, Thomas Gleixner , asavkov@redhat.com, Josh Poimboeuf Cc: davem@davemloft.net, yoshfuji@linux-ipv6.org, Anna-Maria Gleixner , dsahern@kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 0/2] Upper bound kernel timers Date: Wed, 30 Mar 2022 10:20:44 +0200 Message-Id: <20220330082046.3512424-1-asavkov@redhat.com> In-Reply-To: <87zglcfmcv.ffs@tglx> References: <87zglcfmcv.ffs@tglx> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.11.54.1 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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(-)