From owner-freebsd-bugs@freebsd.org Fri Feb 26 17:33:31 2021 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 20686567C7F for ; Fri, 26 Feb 2021 17:33:31 +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 4DnGwC0G6Wz4bwm for ; Fri, 26 Feb 2021 17:33:31 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: by mailman.nyi.freebsd.org (Postfix) id 073275481A6; Fri, 26 Feb 2021 17:33:31 +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 06FE75481B2 for ; Fri, 26 Feb 2021 17:33:31 +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 "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4DnGwB6l53z4bnp for ; Fri, 26 Feb 2021 17:33:30 +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 DA67966FA for ; Fri, 26 Feb 2021 17:33:30 +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 11QHXUnr084622 for ; Fri, 26 Feb 2021 17:33:30 GMT (envelope-from bugzilla-noreply@freebsd.org) Received: (from www@localhost) by kenobi.freebsd.org (8.15.2/8.15.2/Submit) id 11QHXUQS084621 for bugs@FreeBSD.org; Fri, 26 Feb 2021 17:33:30 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 253877] [libgeom] O(n^2) behavior in geom_stats_resync Date: Fri, 26 Feb 2021 17:33:31 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: bin X-Bugzilla-Version: CURRENT X-Bugzilla-Keywords: X-Bugzilla-Severity: Affects Many People X-Bugzilla-Who: asomers@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: 2.1.34 Precedence: list List-Id: Bug reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 26 Feb 2021 17:33:31 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D253877 Bug ID: 253877 Summary: [libgeom] O(n^2) behavior in geom_stats_resync Product: Base System Version: CURRENT Hardware: Any OS: Any Status: New Severity: Affects Many People Priority: --- Component: bin Assignee: bugs@FreeBSD.org Reporter: asomers@FreeBSD.org geom_stats_resync tries to mmap all of /dev/devstat. But without knowing t= hat device's size, it simply tries to mmap successively larger amounts of memory until it fails. That means that the entire operation has O(n^2) syscalls, where n is related to the number of geom providers. On a system with a few thousand providers, running "mdconfig -l" can take several minutes. void geom_stats_resync(void) { void *p; if (statsfd =3D=3D -1) return; for (;;) { p =3D mmap(statp, (npages + 1) * pagesize, PROT_READ, MAP_SHARED, statsfd, 0); if (p =3D=3D MAP_FAILED) break; else statp =3D p; npages++; } } --=20 You are receiving this mail because: You are the assignee for the bug.=