From nobody Tue Apr 21 16:13:42 2026 X-Original-To: dev-commits-src-main@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4g0S8X5WSpz6YRQD for ; Tue, 21 Apr 2026 16:13:48 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "R13" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 4g0S8W4bmKz3hjl for ; Tue, 21 Apr 2026 16:13:47 +0000 (UTC) (envelope-from git@FreeBSD.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1776788027; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=TXk4mil/egs7fFMoKQJp9835cSiXHFG1nuzRb8xQlro=; b=S1SskbZO+VLoATEMAexMU90uyWWOmHBJhpcLLoD8HSpYmPYxEcXqmW4Yub2Y1eCW5eKP68 Ki1+I+RmVxhmwxW7mFb07dCGT8SBfJatD0rywkhM24AVHEtCzIxrHMX66hJ0Fgt4LkD39M HStVPMQwxstqUNJ94UG1CqbEVI08oVYfx9dKuse7XuEEa+qG3nDxHW6novpZ+lYqrmnig+ DMIZu0CRFPdlNg95D3XzD6MCSWryKpjOpefxlI5SQO4O5a8AJmz16ADdMu8bfnQOvo6b6g jjXWJ+bKZwVL+bUMI40zMlcB/ZiialT9c77fcorI/W47OpNaNEth5fNbOi/flw== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1776788027; a=rsa-sha256; cv=none; b=cO4EcyqTotwj1FOgubQRP+ymRgl1PMFodcqrtqBfB8QpwsXHMLbW57W0jI7m2v2faL1Hm3 J/kV6/Fh2CJsyi8RW5l4JP2S9lPjF0r34aBMZTDCDmHPYnVq03F3+B0yq76CFFX1vyUSHY tg7hEjIRuWUdscwO3cp7j7XPbHl53pQrqZxbyfcWROvTgVWx2JYWASESnXBmlOsxh6+byV QXfDfwPSuPRxx+zCNlhhh2tbC8k/fs+hE8Ulyhc1YCQU0BJ2s4TnCkTC+V6gfVI1n9mlbc /14RmmbJefopwe1jc6MWSetuNWHk/6Hu5oABtIrz4XqyxHQDGd3KRYjpFn/3rA== ARC-Authentication-Results: i=1; mx1.freebsd.org; none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1776788027; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=TXk4mil/egs7fFMoKQJp9835cSiXHFG1nuzRb8xQlro=; b=wV0lN+eQqfdligSxp97zpePHBGXoAddIeOzk0y7qtDrJf2/fi5z+Xw6NQ/ZmBRXjv3NVeb XLSo+Feak9YB1nJj2KjNQn0+pDgt6DMEpOrQeMxGSaIdyHEHGkrh45kyBkaXqO8mI+7Ex7 LFbAqnNyB66a3jNdrqBMbPp/wVitLvikFZS1APsu9ICzqzayRiPgOPavvdVIJ16OBSg6ub Hx7tPGxZyBdzFMiPqYqwdQW7q/PUo1pBArbxKUvW9F1K0SIBhG7Um53Shy/2PFXc/OKcy8 7wi5nwg6QnsGrNksJ4itpLTOJXmzZglOutvuj14/XL3Am5UK4ZP3gYxrmCpECQ== Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) by mxrelay.nyi.freebsd.org (Postfix) with ESMTP id 4g0S8W462RzrsC for ; Tue, 21 Apr 2026 16:13:47 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from git (uid 1279) (envelope-from git@FreeBSD.org) id 39248 by gitrepo.freebsd.org (DragonFly Mail Agent v0.13+ on gitrepo.freebsd.org); Tue, 21 Apr 2026 16:13:42 +0000 To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org From: Mark Johnston Subject: git: dce565949914 - main - epoch: Don't idle CPUs when there's pending epoch work List-Id: Commit messages for the main branch of the src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-main List-Help: List-Post: List-Subscribe: List-Unsubscribe: X-BeenThere: dev-commits-src-main@freebsd.org Sender: owner-dev-commits-src-main@FreeBSD.org MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: markj X-Git-Repository: src X-Git-Refname: refs/heads/main X-Git-Reftype: branch X-Git-Commit: dce56594991464c276f340ce963d0f5461566c78 Auto-Submitted: auto-generated Date: Tue, 21 Apr 2026 16:13:42 +0000 Message-Id: <69e7a236.39248.61fb8303@gitrepo.freebsd.org> The branch main has been updated by markj: URL: https://cgit.FreeBSD.org/src/commit/?id=dce56594991464c276f340ce963d0f5461566c78 commit dce56594991464c276f340ce963d0f5461566c78 Author: Mark Johnston AuthorDate: 2026-04-21 14:28:31 +0000 Commit: Mark Johnston CommitDate: 2026-04-21 16:13:19 +0000 epoch: Don't idle CPUs when there's pending epoch work The epoch(9) subsystem implements per-CPU queues of object destructors which get invoked once it is safe to do so. These queues are polled via hardclock(). When a CPU is about to go idle, we reduce the hardclock frequency to 1Hz by default, to avoid unneeded wakeups. This means that if there is any garbage in these destructor queues, it won't be cleared for at least 1s (and possibly longer) even if it would otherwise be safe to do so. epoch_drain_callbacks() is used in some places to provide a barrier, ensuring that all garbage present in the destructor queues is cleaned up before returning. It's implemented by adding a fake destructor in the queues and blocking until it gets run on all CPUs. The above-described phenomenon means that it can take a long time for these calls to return, even (especially) when some CPUs are idle. This causes long delays when destroying VNET jails, for instance, as epoch_drain_callbacks() is invoked each time a network interface is destroyed. Work around this problem by not disabling the hardclock timer if there is garbage present in the destructor queues. The implementation of epoch_drain_callbacks() has other problems, but this small change on its own gives a good improvement, especially when running networking regression tests. Moreover, we should aim to invoke destructors in a timely manner, so the change is generally beneficial. Reviewed by: glebius MFC after: 1 month Differential Revision: https://reviews.freebsd.org/D56508 --- sys/kern/kern_clocksource.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/sys/kern/kern_clocksource.c b/sys/kern/kern_clocksource.c index 6bf3bbd83245..637610654648 100644 --- a/sys/kern/kern_clocksource.c +++ b/sys/kern/kern_clocksource.c @@ -36,6 +36,7 @@ #include #include #include +#include #include #include #include @@ -235,7 +236,7 @@ getnextcpuevent(struct pcpu_state *state, int idle) /* Handle hardclock() events, skipping some if CPU is idle. */ event = state->nexthard; - if (idle) { + if (idle && DPCPU_GET(epoch_cb_count) == 0) { if (tc_min_ticktock_freq > 1 #ifdef SMP && curcpu == CPU_FIRST()