From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 15610 invoked by alias); 1 May 2014 13:28:41 -0000 Mailing-List: contact glibc-bugs-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: glibc-bugs-owner@sourceware.org Received: (qmail 15562 invoked by uid 55); 1 May 2014 13:28:36 -0000 From: "cvs-commit at gcc dot gnu.org" To: glibc-bugs@sourceware.org Subject: [Bug nptl/15119] [arm] unnecessary busy loop in __lll_timedlock_wait on ARM Date: Thu, 01 May 2014 13:28:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: glibc X-Bugzilla-Component: nptl X-Bugzilla-Version: unspecified X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: cvs-commit at gcc dot gnu.org X-Bugzilla-Status: NEW X-Bugzilla-Priority: P2 X-Bugzilla-Assigned-To: bernie.ogden at linaro dot org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Bugzilla-URL: http://sourceware.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-SW-Source: 2014-05/txt/msg00004.txt.bz2 https://sourceware.org/bugzilla/show_bug.cgi?id=15119 --- Comment #3 from cvs-commit at gcc dot gnu.org --- This is an automated email from the git hooks/post-receive script. It was generated because a ref change was pushed to the repository containing the project "GNU C Library master sources". The branch, master has been updated via 6d96f5e4c0500b19d1c2f4edc37536d2bc592260 (commit) from 4fa262fa9e8836f2e513e3ea56797dab2d75e6de (commit) Those revisions listed above that are new to this repository have not appeared on any other notification email; so we list those revisions in full, below. - Log ----------------------------------------------------------------- https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=6d96f5e4c0500b19d1c2f4edc37536d2bc592260 commit 6d96f5e4c0500b19d1c2f4edc37536d2bc592260 Author: Will Newton Date: Thu May 1 14:25:44 2014 +0100 ARM: Remove lowlevellock.c lowlevellock.c for arm differs from the generic lowlevellock.c only in insignificant ways, so can be removed. Happily, this fixes BZ 15119 (unnecessary busy loop in __lll_timedlock_wait on arm). The notable differences between the arm and generic implementations are: 1) arm __lll_timedlock_wait has a fast path out if futex has been set to 0 between since the function was called. This seems unlikely to happen very often, so it seems at worst harmless to lose this fast path. 2) Some function in arm's lowlevellock.c set futex to 2 if it was 1. The generic version always sets the futex to 2. As futex can only be 0, 1 or 2 on entry into these functions, the behaviour is equivalent. (If the futex manages to be 0 on entry then we've just lost another unlikely fast path out.) There are no test suite regressions. Note that hppa and sparc also have their own lowlevellock.c. I believe hppa can also be removed, so I'll send a separate patch for that shortly. sparc's seems to be genuinely needed as it uses a different locking structure. Also note that the analysis at https://sourceware.org/ml/libc-ports/2013-02/msg00021.html indicates a further locking performance bug to fix - I've got a partial patch for that which I can submit once I've finished testing. 2014-05-01 Bernard Ogden [BZ #15119] * sysdeps/unix/sysv/linux/arm/nptl/lowlevellock.c: Remove file. ----------------------------------------------------------------------- Summary of changes: ChangeLog | 6 + sysdeps/unix/sysv/linux/arm/nptl/lowlevellock.c | 132 ----------------------- 2 files changed, 6 insertions(+), 132 deletions(-) delete mode 100644 sysdeps/unix/sysv/linux/arm/nptl/lowlevellock.c -- You are receiving this mail because: You are on the CC list for the bug.