From nobody Tue Oct 28 19:15:56 2025 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 4cx0TS6By1z6DLf4; Tue, 28 Oct 2025 19:15:56 +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 "R12" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4cx0TS5bl3z3ScV; Tue, 28 Oct 2025 19:15:56 +0000 (UTC) (envelope-from git@FreeBSD.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1761678956; 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=RQSOfN7kcRHDEUhyUmPpNKcOcr+cDXH0tQlFOsmc3bQ=; b=UDwaDq1WWtmVahoGo0WX7Zq9WEnr/xMh9LKgb4JAdTfi8aoBHjVuWoQK6+hObpl9GSxbXB OpieKFbOowa4AUmGCUbRc7OPOc4Lcwlp/fmccEmBqv02asnsYIvjKjgmR1HUXX6bPpu6qD jK1ku+x7sgyolylWr3jutJFA8TEQJk+TM5TmxzGticBBR5rEVl5JsZbqsJ0y5g3EuiMmhF e7unXZDn5yhmydwmEZHytcYyubSJtFwR302tlfOWm/87eUMIyTDtHz6Ni/zMQl0ng89Tsz 9Hkkr8c477K2aEg2zC3yQOUFbr2oTVaGGIhrN/9y6NhdocCuvrWg9qEQId8rPQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1761678956; 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=RQSOfN7kcRHDEUhyUmPpNKcOcr+cDXH0tQlFOsmc3bQ=; b=xAte1TPW0jWajXx7RYDxGzauR7KnCqU05fJz/vg3Kw9Pu6WdwC2Kaby0XOU8be0xwPu8Ji rzrum6JtWIpbp7f00lIhq7dYZf6i5jC5N2y5Y0zvadFJc0iKr7PIapSzlbVNwWSakU0FF3 98uk3D1y867oKQ241owh5tlg12NQmdEaO6WpEpFARlYJW+FfPlsM6pd16w55mH9pziFMVw swBqp6j4OI6Vvt3I2EMi2w6P73bio+F4LHYl2FkC96KHr+7fz2Kc8+7DfnOTdB9yCe8v6j Q8+79PptDdvB7e12PgHWX7d9DDMApNfV/0XISBxEuQL7cqyX+wR+2eg6vXbw/w== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1761678956; a=rsa-sha256; cv=none; b=R/I6jFUh1UfAxpOvh6Nvbjj2b8CmQviZ68GxmEUg6g/QE+j/VQBpAoa1fKkbEXwsEHSxxU gaRbBZCTPtqJzm4Y8XBJ3mffm9GYzOx9A4nkqOACFmCbmrUmIJNYhpashsmqSUlLoplaFO JhJfBCEBYVF4Q4oFYPC9GLEyl8lFvC0P3LWUil5OLAvws5lz46nnYAA4N85WAR/j6rKglk G2XmK3KibcTScjfzFvj/bYLWGtVwPzIs9STizmKlMlEnKTDbSItefBcAZQsXfzzbdUGO3R RxaBnMsI/NKi0HOCtL9FoEnlJtKA7MWXBo1/ap7Rv5f12lrW/IJCO+EVyEhbhA== ARC-Authentication-Results: i=1; mx1.freebsd.org; none Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) (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 did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 4cx0TS4vFhz13Py; Tue, 28 Oct 2025 19:15:56 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org ([127.0.1.44]) by gitrepo.freebsd.org (8.18.1/8.18.1) with ESMTP id 59SJFuap031232; Tue, 28 Oct 2025 19:15:56 GMT (envelope-from git@gitrepo.freebsd.org) Received: (from git@localhost) by gitrepo.freebsd.org (8.18.1/8.18.1/Submit) id 59SJFuZo031229; Tue, 28 Oct 2025 19:15:56 GMT (envelope-from git) Date: Tue, 28 Oct 2025 19:15:56 GMT Message-Id: <202510281915.59SJFuZo031229@gitrepo.freebsd.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org From: "Jonathan T. Looney" Subject: git: d83dee356dce - stable/15 - x86: Reduce amount of time the MCA lock is held while emitting records 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: jtl X-Git-Repository: src X-Git-Refname: refs/heads/stable/15 X-Git-Reftype: branch X-Git-Commit: d83dee356dce39b0282bce1f8d7d1ba976995d57 Auto-Submitted: auto-generated The branch stable/15 has been updated by jtl: URL: https://cgit.FreeBSD.org/src/commit/?id=d83dee356dce39b0282bce1f8d7d1ba976995d57 commit d83dee356dce39b0282bce1f8d7d1ba976995d57 Author: Jonathan T. Looney AuthorDate: 2025-10-06 15:07:33 +0000 Commit: Jonathan T. Looney CommitDate: 2025-10-28 19:14:41 +0000 x86: Reduce amount of time the MCA lock is held while emitting records The MCA spin lock is acquired in the hardware interrupt context to record MCA messages. It is also acquired by a task handler to emit those messages. Reduce the amount of time the task handler holds the lock to reduce the maximum amount of time the hardware interrupt handler may need to spin on the lock. Reviewed by: glebius, markj Sponsored by: Netflix Differential Revision: https://reviews.freebsd.org/D52938 (cherry picked from commit e770e32aa3a017b35fcf24e7c6f14fc2a209bad5) --- sys/x86/x86/mca.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) diff --git a/sys/x86/x86/mca.c b/sys/x86/x86/mca.c index e43c88b3a27b..7ee22895e0a7 100644 --- a/sys/x86/x86/mca.c +++ b/sys/x86/x86/mca.c @@ -796,9 +796,9 @@ mca_record_entry(enum scan_mode mode, const struct mca_record *record) mtx_lock_spin(&mca_lock); rec = STAILQ_FIRST(&mca_freelist); if (rec == NULL) { + mtx_unlock_spin(&mca_lock); printf("MCA: Unable to allocate space for an event.\n"); mca_log(record); - mtx_unlock_spin(&mca_lock); return; } STAILQ_REMOVE_HEAD(&mca_freelist, link); @@ -1017,6 +1017,7 @@ static void mca_process_records(enum scan_mode mode) { struct mca_internal *mca; + STAILQ_HEAD(, mca_internal) tmplist; /* * If in an interrupt context, defer the post-scan activities to a @@ -1028,10 +1029,21 @@ mca_process_records(enum scan_mode mode) return; } + /* + * Copy the pending list to the stack so we can drop the spin lock + * while we are emitting logs. + */ + STAILQ_INIT(&tmplist); mtx_lock_spin(&mca_lock); - while ((mca = STAILQ_FIRST(&mca_pending)) != NULL) { - STAILQ_REMOVE_HEAD(&mca_pending, link); + STAILQ_SWAP(&mca_pending, &tmplist, mca_internal); + mtx_unlock_spin(&mca_lock); + + STAILQ_FOREACH(mca, &tmplist, link) mca_log(&mca->rec); + + mtx_lock_spin(&mca_lock); + while ((mca = STAILQ_FIRST(&tmplist)) != NULL) { + STAILQ_REMOVE_HEAD(&tmplist, link); mca_store_record(mca); } mtx_unlock_spin(&mca_lock);