From owner-freebsd-bugs@freebsd.org Mon Aug 26 10:44:10 2019 Return-Path: Delivered-To: freebsd-bugs@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 14849D7595 for ; Mon, 26 Aug 2019 10:44:10 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from mailman.nyi.freebsd.org (mailman.nyi.freebsd.org [IPv6:2610:1c1:1:606c::50:13]) by mx1.freebsd.org (Postfix) with ESMTP id 46H7sj6qHCz4DMV for ; Mon, 26 Aug 2019 10:44:09 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: by mailman.nyi.freebsd.org (Postfix) id E9F0BD7594; Mon, 26 Aug 2019 10:44:09 +0000 (UTC) Delivered-To: bugs@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id E9B71D7593 for ; Mon, 26 Aug 2019 10:44:09 +0000 (UTC) (envelope-from bugzilla-noreply@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) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 46H7sj5rfFz4DMT for ; Mon, 26 Aug 2019 10:44:09 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org (kenobi.freebsd.org [IPv6:2610:1c1:1:606c::50:1d]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id AC1AA4E56 for ; Mon, 26 Aug 2019 10:44:09 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org ([127.0.1.5]) by kenobi.freebsd.org (8.15.2/8.15.2) with ESMTP id x7QAi9ZR004871 for ; Mon, 26 Aug 2019 10:44:09 GMT (envelope-from bugzilla-noreply@freebsd.org) Received: (from www@localhost) by kenobi.freebsd.org (8.15.2/8.15.2/Submit) id x7QAi9L4004870 for bugs@FreeBSD.org; Mon, 26 Aug 2019 10:44:09 GMT (envelope-from bugzilla-noreply@freebsd.org) X-Authentication-Warning: kenobi.freebsd.org: www set sender to bugzilla-noreply@freebsd.org using -f From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 240121] Serial console can eat a lot of cpu with law baudrate Date: Mon, 26 Aug 2019 10:44:09 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: kern X-Bugzilla-Version: 11.2-RELEASE X-Bugzilla-Keywords: X-Bugzilla-Severity: Affects Only Me X-Bugzilla-Who: nicolas.masse@stormshield.eu X-Bugzilla-Status: New X-Bugzilla-Resolution: X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: bugs@FreeBSD.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: bug_id short_desc product version rep_platform op_sys bug_status bug_severity priority component assigned_to reporter Message-ID: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: https://bugs.freebsd.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-BeenThere: freebsd-bugs@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Bug reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 26 Aug 2019 10:44:10 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D240121 Bug ID: 240121 Summary: Serial console can eat a lot of cpu with law baudrate Product: Base System Version: 11.2-RELEASE Hardware: Any OS: Any Status: New Severity: Affects Only Me Priority: --- Component: kern Assignee: bugs@FreeBSD.org Reporter: nicolas.masse@stormshield.eu Since https://svnweb.freebsd.org/base?view=3Drevision&revision=3D317659, de= vices connected through a serial device and using a low baudrate seems to eat a l= ot more cpu than before. This has been constated using a lcd screen with a baudrate of 2400. Using pmc, I got this: PMC: [CPU_CLK_UNHALTED.THREAD_P] Samples: 14 (100.0%) , 0 unresolved %SAMP CALLTREE 85.7 amd64_syscall@kernel sys_write kern_writev dofilewrite devfs_write_f ttydev_write ttydisc_write tty_wait _cv_wait_sig __mtx_lock_sleep lock_delay(85.7%)=20 7.1 _start@xxx (7.1%)=20 7.1 _start@xxx (7.1%)=20 Reverting this commit made the call to lock_delay disappear and the performances of my test system back to normal. --=20 You are receiving this mail because: You are the assignee for the bug.=