From nobody Tue Apr 21 16:13:42 2026 X-Original-To: dev-commits-src-all@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 4g0S8Q5MfFz6WxmQ for ; Tue, 21 Apr 2026 16:13:42 +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 4g0S8Q4nb7z3hxF for ; Tue, 21 Apr 2026 16:13:42 +0000 (UTC) (envelope-from git@FreeBSD.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1776788022; 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=qzXxKMjyBzOLejxZy8/8m8gcn9GYp8MRtpfS0/90Fnwev7P6kVdIkXL5xmSTHKJPc069I5 BY05Z3xh7Jv9b3xjA0Mzrct9+Hb4/mpKnaaDFdC5txfRbEB1JRLEX4Cabmtcu5ZTWPnZOz ed/TZWtKN3JFMM+fLmWTg89sL8EoF50eGJEfwzQhu1rKT8aWoWxh36pI3Kfu05tG41sPtr AXpZ5SeVlnPKv6C7I28kzlx84p7q5KJ7/beM8Qb87iclfRwXnj3K557m1OtOsUAV69S8d6 Qlrtb/PRNNVqsacxzc+EeAK5buesiPotDu55qLw69z+FQ2vsyw99h431QGVDZw== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1776788022; a=rsa-sha256; cv=none; b=cRureubYEcwR42ymIAklJVFtuJGrG9FL+XXQM1jdkX3RwxlrYp61SyIY5MgFuaqFqtvcMZ 2PNgOW7um4x8KiqBz47uZ7/bqAZ7Pna6VYg/Y59qurgP6fGe7PP6/mvpuv4ZhEwkPxKGpX vS5i7Qyh4bGQkX/kzS9Dlm+qPmU9hRU2tQraiaUnr4K5OshmFLRultgUz5SjvSy/tL81JR vzSSEr+xsQHYT34RDbLkqzF0rJkbjtchxwtzbBC1b5FC1EgNf9gfUKFRb28/Iw9x0SEXKo oY8G2lwm2LQ+ylE4lJEFNChdWXcWp/WJiv4iIB0ciEgkAm0vIQdRPzhqgzFXbw== 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=1776788022; 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=oFL5+oYp7LPPuDn2JqV/KByXAfvmTJZEeGwhGwYpAkT+NpfNtsDAHXqZbELuTGncgeqpt0 hLvy9zQKSLWMDEpbAdIeYnUww3jTFhUA4Esdx1GV4t6+QhUPgBoVnAw4Ha4MZ0yOhhBoKN fJ/nVclVsnftd1vE3n3PMVQGqQNWLAjn+iCu0nHFb596TB+TNL7BnbbiNXSPLZBLQY2cy8 wkxLVy7V2VtqqRdLoLcS4BGfcGJ5fUc/kmPe9ADjH5HtzK5ZAQslVUQskAYHOJMf4ojguf DDSQbnK/YiTfSGmx8BJnLtrlZA9ynGJIPeBCVrgiMcMRPkP0urVvNPGDsB6HFA== Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) by mxrelay.nyi.freebsd.org (Postfix) with ESMTP id 4g0S8Q44wCzrXp for ; Tue, 21 Apr 2026 16:13:42 +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 all branches of the src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-all List-Help: List-Post: List-Subscribe: List-Unsubscribe: X-BeenThere: dev-commits-src-all@freebsd.org Sender: owner-dev-commits-src-all@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()