Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1031070AbbDXTtK (ORCPT ); Fri, 24 Apr 2015 15:49:10 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:54808 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756241AbbDXTtH (ORCPT ); Fri, 24 Apr 2015 15:49:07 -0400 Date: Fri, 24 Apr 2015 12:49:05 -0700 From: Andrew Morton To: Hagen Paul Pfeifer Cc: linux-kernel@vger.kernel.org, Ingo Molnar , "H. Peter Anvin" , "David S. Miller" , "Paul E. McKenney" , x86@kernel.org Subject: Re: [PATCH] enforce function inlining for hot functions Message-Id: <20150424124905.07e29a3b1392513144cd1568@linux-foundation.org> In-Reply-To: <1429825201-2825-1-git-send-email-hagen@jauu.net> References: <1429825201-2825-1-git-send-email-hagen@jauu.net> X-Mailer: Sylpheed 3.4.1 (GTK+ 2.24.23; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1530 Lines: 36 On Thu, 23 Apr 2015 23:40:01 +0200 Hagen Paul Pfeifer wrote: > GCC inlining heuristics are sometimes quizzical. Especially with inline > assembler constructs GCC seems to have issues. A allyesconfig show a rather > long list of functions where GCC inlining decisions are questionable (not > inlined). I can't reproduce this with either gcc-4.8.2 or gcc-4.4.4. The patch makes zero difference to `size vmlinux' and a bit of poking around with nm doesn't show any out-of-lined versions of the functions you identify. So. More details, please. How to demonstrate this, gcc versions, etc. > Furthermore, because the functions are declared with static > linkage each function is copied n times - and n can be rather high: > > atomic_inc: 544 duplicates > rcu_read_unlock: 453 duplicates > rcu_read_lock: 383 duplicates > get_dma_ops: 271 duplicates > arch_local_irq_restore: 258 duplicates > atomic_dec: 215 duplicates > kzalloc: 185 duplicates > cpumask_check: 157 duplicates > test_and_set_bit: 156 duplicates > cpumask_next: 146 duplicates > list_del: 131 duplicates > kref_get: 126 duplicates That's pretty pathetic. -- 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/