From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762786AbXGXTlh (ORCPT ); Tue, 24 Jul 2007 15:41:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754919AbXGXTl0 (ORCPT ); Tue, 24 Jul 2007 15:41:26 -0400 Received: from mailout.stusta.mhn.de ([141.84.69.5]:43334 "EHLO mailhub.stusta.mhn.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752204AbXGXTlZ (ORCPT ); Tue, 24 Jul 2007 15:41:25 -0400 Date: Tue, 24 Jul 2007 21:40:46 +0200 From: Adrian Bunk To: Linus Torvalds Cc: Andrew Morton , Alexey Dobriyan , linux-kernel@vger.kernel.org, netdev@vger.kernel.org Subject: Re: 2.6.23-rc1: BUG_ON in kmap_atomic_prot() Message-ID: <20070724194046.GD6019@stusta.de> References: <20070723190152.GA5755@martell.zuzino.mipt.ru> <20070723132431.42afbae8.akpm@linux-foundation.org> <20070723204045.GD5755@martell.zuzino.mipt.ru> <20070723210153.GA5753@martell.zuzino.mipt.ru> <20070723141137.171e4ac1.akpm@linux-foundation.org> <20070724175951.GC6019@stusta.de> <20070724112843.0cc104c2.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.16 (2007-06-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 24, 2007 at 12:15:48PM -0700, Linus Torvalds wrote: > > > On Tue, 24 Jul 2007, Andrew Morton wrote: > > > > fwiw, -fno-inline-functions-called-once (who knew?) takes i386 allnoconfig > > vmlinux .text from 928360 up to 955362 bytes (27k larger). > > > > A surprisingly large increase - I wonder if it did something dumb. It > > appears to still correctly inline those things which we've manually marked > > inline. hm. > > I think inlining small enough functions is worth it, and the thing is, the > kernel is actually pretty damn good at having lots of small functions. > It's one of the few things I really care about from a coding style > standpoint. > > So I'm not surprised that "-fno-inline-functions-called-once" makes things > larger, because I think it's generally a good idea to inline things that > are just called once. But it does make things harder to debug, and the > performance advantages become increasingly small for bigger functions. > > And that's a balancing act. Do we care about performance? Yes. When using CONFIG_CC_OPTIMIZE_FOR_SIZE=y we even actively tell gcc that we only care about size and do not care about performance... > But do we > care so much that it's worth inlining something like buffered_rmqueue()? >... Where is the problem with having buffered_rmqueue() inlined? > Linus cu Adrian -- "Is there not promise of rain?" Ling Tan asked suddenly out of the darkness. There had been need of rain for many days. "Only a promise," Lao Er said. Pearl S. Buck - Dragon Seed