Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754428Ab3GAOg7 (ORCPT ); Mon, 1 Jul 2013 10:36:59 -0400 Received: from mail.skyhub.de ([78.46.96.112]:54954 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752448Ab3GAOg5 (ORCPT ); Mon, 1 Jul 2013 10:36:57 -0400 Date: Mon, 1 Jul 2013 16:36:47 +0200 From: Borislav Petkov To: "H. Peter Anvin" Cc: Ingo Molnar , Wedson Almeida Filho , Ingo Molnar , Thomas Gleixner , x86@kernel.org, linux-kernel@vger.kernel.org, Linus Torvalds , Andrew Morton , Peter Zijlstra Subject: Re: [PATCH] x86: Use asm-goto to implement mutex fast path on x86-64 Message-ID: <20130701143646.GG23515@pd.tnic> References: <1372416851-56830-1-git-send-email-wedsonaf@gmail.com> <20130628111948.GA31065@gmail.com> <20130628140938.GA24819@pd.tnic> <20130630220004.GA23124@pd.tnic> <20130701075046.GB1681@gmail.com> <20130701102306.GC23515@pd.tnic> <19b76ce4-35e0-4f82-b7e9-aa07d5d8af2c@email.android.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <19b76ce4-35e0-4f82-b7e9-aa07d5d8af2c@email.android.com> 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 Content-Length: 1155 Lines: 36 On Mon, Jul 01, 2013 at 07:30:14AM -0700, H. Peter Anvin wrote: > Unconditional branches don't need prediction. The branch predictor > is used for conditional branches and in some hardware designs for > indirect branches. Unconditional direct branches never go through > the branch predictor simply because the front end can know with 100% > certainty where the flow of control will be. I meant the conditional Jcc branches: ffffffff81774920 : ... ffffffff8177492d: f0 ff 0b lock decl (%rbx) ffffffff81774930: 79 08 jns ffffffff8177493a ffffffff81774730 : ... ffffffff81774738: f0 ff 07 lock incl (%rdi) ffffffff8177473b: 7f 0a jg ffffffff81774747 -- Regards/Gruss, Boris. Sent from a fat crate under my desk. Formatting is fine. -- -- 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/