Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755867AbaJHRFW (ORCPT ); Wed, 8 Oct 2014 13:05:22 -0400 Received: from cassarossa.samfundet.no ([193.35.52.29]:54542 "EHLO cassarossa.samfundet.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754842AbaJHRFU (ORCPT ); Wed, 8 Oct 2014 13:05:20 -0400 Date: Wed, 8 Oct 2014 19:05:13 +0200 From: "Steinar H. Gunderson" To: Linus Torvalds Cc: Mike Galbraith , Linux Kernel Mailing List , Peter Zijlstra , Thomas Gleixner Subject: Re: bisected: futex regression >= 3.14 - was - Slowdown due to threads bouncing between HT cores Message-ID: <20141008170513.GA13720@sesse.net> References: <20141003194428.GA27084@sesse.net> <1412782664.5179.75.camel@marge.simpson.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: X-Operating-System: Linux 3.16.3 on a x86_64 User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 08, 2014 at 01:04:01PM -0400, Linus Torvalds wrote: > So like Thomas, I would suspect a race condition in the futex use, and > then the exact futex implementation details are just exposing it > incidentally. FWIW, Stockfish does not use futex directly; it uses pthreads (or Win32 threads if you are on that OS :-) ). That doesn't preclude a race condition somewhere, of course. /* Steinar */ -- Homepage: http://www.sesse.net/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/