From owner-freebsd-bugs@freebsd.org Sun Aug 20 07:19:30 2017 Return-Path: Delivered-To: freebsd-bugs@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 2156FDE46BE for ; Sun, 20 Aug 2017 07:19:30 +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 mx1.freebsd.org (Postfix) with ESMTPS id 0F65876D2A for ; Sun, 20 Aug 2017 07:19:30 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from bugs.freebsd.org ([127.0.1.118]) by kenobi.freebsd.org (8.15.2/8.15.2) with ESMTP id v7K7JTUG099983 for ; Sun, 20 Aug 2017 07:19:29 GMT (envelope-from bugzilla-noreply@freebsd.org) From: bugzilla-noreply@freebsd.org To: freebsd-bugs@FreeBSD.org Subject: [Bug 221029] AMD Ryzen: strange compilation failures using poudriere or plain buildkernel/buildworld Date: Sun, 20 Aug 2017 07:19:29 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: kern X-Bugzilla-Version: 11.1-RELEASE X-Bugzilla-Keywords: X-Bugzilla-Severity: Affects Some People X-Bugzilla-Who: truckman@FreeBSD.org X-Bugzilla-Status: New X-Bugzilla-Resolution: X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: freebsd-bugs@FreeBSD.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: 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: 2.1.23 Precedence: list List-Id: Bug reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 20 Aug 2017 07:19:30 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D221029 --- Comment #80 from Don Lewis --- The events controlled by kern.sched.balance are timer based and are probably much less frequent than occurences of a CPU running out of work to do and triggering a steal_idle event unless the machine has a very high load avera= ge so that all of the CPUs have long queues of runnable processes. Since I do= n't really care about scheduling fairness in these experiments, I'm planning on leaving kern.sched.balance=3D0. I think that kern.sched.steal_idle is much= more interesting. In order to make the experiments as meaningful as possible, I= 'd like to keep the overall CPU idle time as low as possible. If there is a l= ot of CPU idle time with kern.sched.steal_idle=3D0, then the reduction of memo= ry bandwidth demand and lower die temperature can confuse the results. Based on my previous experiment, I suspect that steal_idle events ignore the CPU affinity time setting, which sort of makes sense. In my latest experiment, I set kern.sched.affinity=3D10 and set both steal_= idle and balance back to 0. This time ghc successfully built, which I attribute= to a lucky roll of the dice. During the lang/ghc build, ghc (either the boots= trap or newly built version) gets executing a number of times. How many times it succeeds before eventually getting a SIGBUS seems random. What is somewhat surprising is that once built, ghc was able to successfully able to build a large number of hs_* ports without any failures. This time chromium also avoided the rename issue and built successfully. The only failure was lang= /go, which has also failed frequently on my Ryzen machine. I think the lang/ghc= and lang/go issues are distinct with the other random build problems. What would be interesting would be to dig into sched_ule and tweak steal_id= le to restrict the CPUs that it can steal tasks from. One experiment would be= to only allow it to steal from the other thread on the same CPU core. Another would be to only allow it to steal from a core in the same CCX. --=20 You are receiving this mail because: You are the assignee for the bug.=