From owner-freebsd-bugs@freebsd.org Fri May 29 19:33:26 2020 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 BE0A133FE2B for ; Fri, 29 May 2020 19:33:26 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from mailman.nyi.freebsd.org (unknown [127.0.1.3]) by mx1.freebsd.org (Postfix) with ESMTP id 49YZVZ4kdBz4J7y for ; Fri, 29 May 2020 19:33:26 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: by mailman.nyi.freebsd.org (Postfix) id A255C2F0002; Fri, 29 May 2020 19:33:26 +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 A115933FE2A for ; Fri, 29 May 2020 19:33:26 +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) 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 "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 49YZVZ3nLLz4JN9 for ; Fri, 29 May 2020 19:33:26 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org (kenobi.freebsd.org [IPv6:2610:1c1:1:606c::50:1d]) (using TLSv1.3 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 6344A1CEE6 for ; Fri, 29 May 2020 19:33:26 +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 04TJXQTu097864 for ; Fri, 29 May 2020 19:33:26 GMT (envelope-from bugzilla-noreply@freebsd.org) Received: (from www@localhost) by kenobi.freebsd.org (8.15.2/8.15.2/Submit) id 04TJXQvK097863 for bugs@FreeBSD.org; Fri, 29 May 2020 19:33:26 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 246630] stable/11 regression: base.txz reproducibility depends on number of cpu cores Date: Fri, 29 May 2020 19:33:24 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: bin X-Bugzilla-Version: Unspecified X-Bugzilla-Keywords: regression X-Bugzilla-Severity: Affects Some People X-Bugzilla-Who: dim@FreeBSD.org X-Bugzilla-Status: Open X-Bugzilla-Resolution: X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: bugs@FreeBSD.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: bug_status 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: 2.1.33 Precedence: list List-Id: Bug reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 29 May 2020 19:33:26 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D246630 Dimitry Andric changed: What |Removed |Added ---------------------------------------------------------------------------- Status|New |Open --- Comment #18 from Dimitry Andric --- So after quite a bit of head scratching, I found that the problem appears t= o be caused by upstream commit https://github.com/llvm/llvm-project/commit/b4a99a061f517e60985667e39519f60= 186cbb469: commit b4a99a061f517e60985667e39519f60186cbb469 Author: Alexandre Ganea Date: Mon Jan 13 10:40:04 2020 -0500 [Clang][Driver] Re-use the calling process instead of creating a new process for the cc1 invocation With this patch, the clang tool will now call the -cc1 invocation direc= tly inside the same process. Previously, the -cc1 invocation was creating, and waiting for, a new process. This patch therefore reduces the number of created processes during a build, thus it reduces build times on platforms where process creation can = be costly (Windows) and/or impacted by a antivirus. It also makes debugging a bit easier, as there's no need to attach to t= he secondary -cc1 process anymore, breakpoints will be hit inside the same process. Crashes or signaling inside the -cc1 invocation will have the same side-effect as before, and will be reported through the same means. This behavior can be controlled at compile-time through the CLANG_SPAWN= _CC1 cmake flag, which defaults to OFF. Setting it to ON will revert to the prev= ious behavior, where any -cc1 invocation will create/fork a secondary process. At run-time, it is also possible to tweak the CLANG_SPAWN_CC1 environme= nt variable. Setting it and will override the compile-time setting. A value of= 0 calls -cc1 inside the calling process; a value of 1 will create a secondary process, as before. Differential Revision: https://reviews.llvm.org/D69825 For some reason, not spawning a second process for the cc1 stage has this particular influence on the end result, and *only* for the printf.c file! I'm still digging further into this rabbit hole, but for now a good workaro= und is to set the environment variable CLANG_SPAWN_CC1=3D1. This forces the cla= ng driver to fork and exec a new instance for the cc1 stage, and clears up the problem completely for me. --=20 You are receiving this mail because: You are the assignee for the bug.=