From owner-freebsd-bugs@freebsd.org Mon Mar 4 22:07:57 2019 Return-Path: Delivered-To: freebsd-bugs@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id E7CE11524C0C for ; Mon, 4 Mar 2019 22:07:56 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from mailman.ysv.freebsd.org (mailman.ysv.freebsd.org [IPv6:2001:1900:2254:206a::50:5]) by mx1.freebsd.org (Postfix) with ESMTP id 68CBB8B18A for ; Mon, 4 Mar 2019 22:07:56 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: by mailman.ysv.freebsd.org (Postfix) id 2758C1524C01; Mon, 4 Mar 2019 22:07:56 +0000 (UTC) Delivered-To: bugs@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 1341E1524C00 for ; Mon, 4 Mar 2019 22:07:56 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from mxrelay.ysv.freebsd.org (mxrelay.ysv.freebsd.org [IPv6:2001:1900:2254:206a::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.ysv.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 99CFA8B187 for ; Mon, 4 Mar 2019 22:07:55 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org (kenobi.freebsd.org [IPv6:2001:1900:2254:206a::16:76]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.ysv.freebsd.org (Postfix) with ESMTPS id D434811D9A for ; Mon, 4 Mar 2019 22:07:54 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org ([127.0.1.118]) by kenobi.freebsd.org (8.15.2/8.15.2) with ESMTP id x24M7sVe018378 for ; Mon, 4 Mar 2019 22:07:54 GMT (envelope-from bugzilla-noreply@freebsd.org) Received: (from www@localhost) by kenobi.freebsd.org (8.15.2/8.15.2/Submit) id x24M7sZA018377 for bugs@FreeBSD.org; Mon, 4 Mar 2019 22:07:54 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 236233] Python multiprocessing is 20x slower with 11.2 compared to 11.0 kernel Date: Mon, 04 Mar 2019 22:07:54 +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: arichardson@FreeBSD.org 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, 04 Mar 2019 22:07:57 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D236233 Bug ID: 236233 Summary: Python multiprocessing is 20x slower with 11.2 compared to 11.0 kernel 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: arichardson@FreeBSD.org After I updated our jenkins slaves from 11.0 to 11.2 running the LLVM regression test suite takes over 2 hours instead of 5-10 minutes. The testsuite is driven by llvm-lit (a python script) that makes heavy use = of python multiprocessing module. On 11.0 the test output prints status updates all the time whereas on 11.2 = it will print N (or N-1, N-2) status updates (with N being the number of paral= lel jobs) before a noticeable pause. In that pause it seems like the individual python processes start using 100% CPU. I tried updating one of the slaves to 12.0 but it is still just as slow. I also tried updating python27 to the latest 11.2 package (2.7.15) but that still runs fast. Therefore it seems to me like this could be a regression w= ith semaphores or umtx. I am also not sure if this is a regression in the kernel or libc/libthr. Downgrading to 11.0 fixes the issue. --=20 You are receiving this mail because: You are the assignee for the bug.=