From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx151.postini.com [74.125.245.151]) by kanga.kvack.org (Postfix) with SMTP id 0C2636B005D for ; Wed, 26 Sep 2012 17:51:29 -0400 (EDT) Received: by ied10 with SMTP id 10so3388769ied.14 for ; Wed, 26 Sep 2012 14:51:29 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20120926144219.bf4bfb9d.akpm@linux-foundation.org> References: <1347137279-17568-1-git-send-email-elezegarcia@gmail.com> <1347137279-17568-5-git-send-email-elezegarcia@gmail.com> <20120925142948.6b062cb6.akpm@linux-foundation.org> <20120926144219.bf4bfb9d.akpm@linux-foundation.org> Date: Wed, 26 Sep 2012 18:51:29 -0300 Message-ID: Subject: Re: [PATCH 05/10] mm, util: Use dup_user to duplicate user memory From: Ezequiel Garcia Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Pekka Enberg Andrew, On Wed, Sep 26, 2012 at 6:42 PM, Andrew Morton wrote: > On Tue, 25 Sep 2012 22:15:38 -0300 > Ezequiel Garcia wrote: > >> > This patch increases util.o's text size by 238 bytes. A larger kernel >> > with a worsened cache footprint. >> > >> > And we did this to get marginally improved tracing output? This sounds >> > like a bad tradeoff to me. >> > >> >> Mmm, that's bad tradeoff indeed. >> It's certainly odd since the patch shouldn't increase the text size >> *that* much. >> Is it too much to ask that you send your kernel config and gcc version. > > x86_64 allmodconfig with CONFIG_DEBUG_INFO=n, > CONFIG_ENABLE_MUST_CHECK=n. gcc-4.4.4. > I'll try that. >> My compilation (x86 kernel in gcc 4.7.1) shows a kernel less bloated: >> >> $ readelf -s util-dup-user.o | grep dup_user >> 161: 00001c10 108 FUNC GLOBAL DEFAULT 1 memdup_user >> 169: 00001df0 159 FUNC GLOBAL DEFAULT 1 strndup_user >> $ readelf -s util.o | grep dup_user >> 161: 00001c10 108 FUNC GLOBAL DEFAULT 1 memdup_user >> 169: 00001df0 98 FUNC GLOBAL DEFAULT 1 strndup_user >> >> $ size util.o >> text data bss dec hex filename >> 18319 2077 0 20396 4fac util.o >> $ size util-dup-user.o >> text data bss dec hex filename >> 18367 2077 0 20444 4fdc util-dup-user.o >> >> Am I doing anything wrong? > > Dunno - it could be a config thing. > I'm kind of lost. The patch really shouldn't fatten the kernel this way :-( The patch was meant to improve tracing for memory tracking, which in turn would be used to reduce memory footprint. So, definitely I don't want to increase kernel text size. I'll test that kernel config and see what I can do. Thanks, Ezequiel. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org