From nobody Tue Oct 28 21:23:40 2025 X-Original-To: dev-commits-src-branches@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 4cx3Js3Fn8z6DVhj; Tue, 28 Oct 2025 21:23:41 +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 4cx3Js0sFzz3lVR; Tue, 28 Oct 2025 21:23:41 +0000 (UTC) (envelope-from git@FreeBSD.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1761686621; 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=SdT0cEMSF2yW7u7jetJDE++97oP8MxOcY5rb/3FT24A=; b=iOOkuQSPqAOiNjTBT9RBZv8Upc900r3yHf3ZLmCb1+xzPEtNzaJiPfAEF68fghGOiupNuv m43efB19lmrewNHOGu7nI4W9LEnLdgfYSwcId1k4lNP1xyfwTaFUojcM11QgorPXPli46k /9vbPxT8nwJiXT5Brrwp7qTWn874BkNlqXNv325aq7797gNktlHF6u2WZCZanMrRqrlCKd cWgIvAzQtyDSywP3rSKEn0+hGtagirGTwVYQGTyU7WMTborvpXilRE9zkXu6LEkHT8ZA2b mHv8Oy8KgM0EDp0ChoNyuMbWA88fKe168O/7vW1gvoODg1Z0v7roLpzeRlEnyQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1761686621; 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=SdT0cEMSF2yW7u7jetJDE++97oP8MxOcY5rb/3FT24A=; b=TH4Fvs7O843D85jnKYlPgwnQj9t19MduNHDyKQmRnVrY3n85r2tkusvvzWTxmK5mBcMNIj /eV/DNmT+F+ZsNOmbPEbedSSwvwmBohlNqm0Z/M2M0XAgAvwE6NOgDIYRQCjDSryLojAX+ DLbayHdHy15ZQ6InpQ5ieoU3uD1Nv16Ji49P0GSaGHIMzoltrqi3VR/MZFIM+8BEdXDrhr ZDboLIJPMAwTU7AHSVYubCri0JIRtnLhYMJr+6yXOXRDAi2en/TEwqAjJH1pHb/BpYnoPe /HDHbOO6Qn+JypAuuxO6uxPWlmY32f3HiNsasBlzyysRlT7ClQQ2auK2vg/99A== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1761686621; a=rsa-sha256; cv=none; b=SAcbKFfLEoyw/lm4NmWHrb7MZ9r2JXU/pj2zq7xueF8N1da8fuYGvum7h6EzAk30vRqUQk lttBmHq4gJzU9PgW3i+Lm4TA8telCP5cbS2+fbn/EKqZgEjKJr0sTWmxYl2xsumzCsEx7c b/lza4RtiWtBbdUpVSbcpbS+7bcoiLIIRKf8+8vcYy1VVW1xIpP8p0rzPHFosRwyqOl+vd FTu3/enXm0/+/iC71FO+pcL9DoH2biK73ofOoRquL9uGM0+w1/0LHkJs1Sj0vur47d7pst EnvhEKhGysgEVHyl23NNcbdmpblwAjaHLkzRQYkUcto//ysKPAcF34fN3hw44Q== 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 4cx3Js06C8z16S6; Tue, 28 Oct 2025 21:23:41 +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 59SLNer1075621; Tue, 28 Oct 2025 21:23:40 GMT (envelope-from git@gitrepo.freebsd.org) Received: (from git@localhost) by gitrepo.freebsd.org (8.18.1/8.18.1/Submit) id 59SLNeQM075618; Tue, 28 Oct 2025 21:23:40 GMT (envelope-from git) Date: Tue, 28 Oct 2025 21:23:40 GMT Message-Id: <202510282123.59SLNeQM075618@gitrepo.freebsd.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org From: Colin Percival Subject: git: 8376d05279ee - releng/15.0 - x86: Reduce amount of time the MCA lock is held while emitting records List-Id: Commits to the stable branches of the FreeBSD src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-branches List-Help: List-Post: List-Subscribe: List-Unsubscribe: X-BeenThere: dev-commits-src-branches@freebsd.org Sender: owner-dev-commits-src-branches@FreeBSD.org MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: cperciva X-Git-Repository: src X-Git-Refname: refs/heads/releng/15.0 X-Git-Reftype: branch X-Git-Commit: 8376d05279ee78e39f8face7b307772c8c306fa7 Auto-Submitted: auto-generated The branch releng/15.0 has been updated by cperciva: URL: https://cgit.FreeBSD.org/src/commit/?id=8376d05279ee78e39f8face7b307772c8c306fa7 commit 8376d05279ee78e39f8face7b307772c8c306fa7 Author: Jonathan T. Looney AuthorDate: 2025-10-06 15:07:33 +0000 Commit: Colin Percival CommitDate: 2025-10-28 21:23:05 +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. Approved by: re (cperciva) Reviewed by: glebius, markj Sponsored by: Netflix Differential Revision: https://reviews.freebsd.org/D52938 (cherry picked from commit e770e32aa3a017b35fcf24e7c6f14fc2a209bad5) (cherry picked from commit d83dee356dce39b0282bce1f8d7d1ba976995d57) --- 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);