Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751904AbaB1UT4 (ORCPT ); Fri, 28 Feb 2014 15:19:56 -0500 Received: from mail-vc0-f169.google.com ([209.85.220.169]:39746 "EHLO mail-vc0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751576AbaB1UTy (ORCPT ); Fri, 28 Feb 2014 15:19:54 -0500 MIME-Version: 1.0 In-Reply-To: References: <2f5d45b67dcd2c4ba58ed7ff13cfcd7a4da977fa.1393545985.git.luto@amacapital.net> <1393572505.1019.10.camel@wall-e.seibold.net> From: Andy Lutomirski Date: Fri, 28 Feb 2014 12:19:34 -0800 Message-ID: Subject: Re: [PATCH v2 1/4] x86: Use the default ABI for the 32-bit vDSO To: "H. Peter Anvin" Cc: Stefani Seibold , X86 ML , Greg KH , "linux-kernel@vger.kernel.org" , Thomas Gleixner , Ingo Molnar , Andi Kleen , Andrea Arcangeli , John Stultz , Pavel Emelyanov , Cyrill Gorcunov , andriy.shevchenko@linux.intel.com, Martin.Runge@rohde-schwarz.com, Andreas.Brief@rohde-schwarz.com Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 28, 2014 at 7:06 AM, H. Peter Anvin wrote: > How many internal function calls are there? It seems we should try to avoid those as much as possible by suitable inlining. There are no non-static calls at all, except for __x86.get_pc_thunk. I imagine that gcc is smart enough to improve the calling convention to non-externally-visible functions. Amazingly (to me, anyway), the performance of the 32-bit version seems to be within 1 ns or so of the 64-bit version on SNB. I suspect that Intel has optimized the crap out of these things. --Andy -- 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/