Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756556Ab0HaBgb (ORCPT ); Mon, 30 Aug 2010 21:36:31 -0400 Received: from mail-iw0-f174.google.com ([209.85.214.174]:38401 "EHLO mail-iw0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756473Ab0HaBg3 convert rfc822-to-8bit (ORCPT ); Mon, 30 Aug 2010 21:36:29 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=qg5nMIRhOg/s1YcjdKqS9Pl3bNZAte/hGSeR93Xl3TvaP2ilCPjbU75bHz5QikrOUK 5lBznlkhx+CCNJ+sAWHUHZb34WgeWr1wT0ECSxdK520KKfR8kkfppMkN629FcrIrVCQ5 hCi0jTq+QHWYM+keFAekBsvNvw9C46kOo1NnU= MIME-Version: 1.0 In-Reply-To: <20100831101456.87D0.A69D9226@jp.fujitsu.com> References: <20100831095542.87CA.A69D9226@jp.fujitsu.com> <20100831101456.87D0.A69D9226@jp.fujitsu.com> Date: Tue, 31 Aug 2010 10:36:25 +0900 Message-ID: Subject: Re: [PATCH] vmscan: prevent background aging of anon page in no swap system From: Minchan Kim To: KOSAKI Motohiro Cc: Ying Han , Rik van Riel , Andrew Morton , linux-mm , LKML , Venkatesh Pallipadi , Johannes Weiner Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4257 Lines: 98 On Tue, Aug 31, 2010 at 10:18 AM, KOSAKI Motohiro wrote: >> Hi, KOSAKI. >> >> On Tue, Aug 31, 2010 at 9:56 AM, KOSAKI Motohiro >> wrote: >> >> diff --git a/mm/vmscan.c b/mm/vmscan.c >> >> index 1b145e6..0b8a3ce 100644 >> >> --- a/mm/vmscan.c >> >> +++ b/mm/vmscan.c >> >> @@ -1747,7 +1747,7 @@ static void shrink_zone(int priority, struct zone *zone, >> >> ? ? ? ? ?* Even if we did not try to evict anon pages at all, we want to >> >> ? ? ? ? ?* rebalance the anon lru active/inactive ratio. >> >> ? ? ? ? ?*/ >> >> - ? ? ? if (inactive_anon_is_low(zone, sc) && nr_swap_pages > 0) >> >> + ? ? ? if (nr_swap_pges > 0 && inactive_anon_is_low(zone, sc)) >> > >> > Sorry, I don't find any difference. What is your intention? >> > >> >> My intention is that smart gcc can compile out inactive_anon_is_low >> call in case of non swap configurable system. > > Do you really check it on your gcc? nr_swap_pages is not file scope variable, it's > global variable. afaik, current gcc's link time optimization is not so cool. #else /* CONFIG_SWAP */ #define nr_swap_pages 0L #define total_swap_pages 0L #define total_swapcache_pages 0UL > > Do you have a disassemble list? > environment for test : gcc : arm-none-linux-gnueabi-gcc (Sourcery G++ Lite 2009q3-67) 4.4.1 kernel : 2.6.28(for test, I used my working kernel version with my patch) assembled function is shrink_zone. (Please understand web gmail's contents mangling. Google guys! Please repair for like me who can't use SMTP in company. :( ) 1. swap configurable version 1cd0: e51b303c ldr r3, [fp, #-60] ; 0x3c 1cd4: e3530000 cmp r3, #0 1cd8: 1affffd1 bne 1c24 1cdc: e5879004 str r9, [r7, #4] 1ce0: e1a00008 mov r0, r8 1ce4: e1a01007 mov r1, r7 1ce8: e1a04008 mov r4, r8 1cec: ebfff8eb bl a0 <== 1cf0: e1a05007 mov r5, r7 1cf4: e3500000 cmp r0, #0 1cf8: 0a000006 beq 1d18 1cfc: e1a01008 mov r1, r8 1d00: e1a03006 mov r3, r6 1d04: e3a00020 mov r0, #32 1d08: e1a02007 mov r2, r7 1d0c: e3a0c000 mov ip, #0 1d10: e58dc000 str ip, [sp] 1d14: ebfffa98 bl 77c 1d18: e5950008 ldr r0, [r5, #8] 1d1c: ebfffffe bl 0 1d20: e24bd028 sub sp, fp, #40 ; 0x28 2. non swap configurable version 1994: e3530000 cmp r3, #0 1998: 0a000003 beq 19ac 199c: e598300c ldr r3, [r8, #12] 19a0: e593300c ldr r3, [r3, #12] 19a4: e3130701 tst r3, #262144 ; 0x40000 19a8: 0a000008 beq 19d0 19ac: e51b3044 ldr r3, [fp, #-68] ; 0x44 19b0: e3530000 cmp r3, #0 19b4: 1affffd7 bne 1918 19b8: e51b3038 ldr r3, [fp, #-56] ; 0x38 19bc: e3530000 cmp r3, #0 19c0: 1affffd4 bne 1918 19c4: e51b303c ldr r3, [fp, #-60] ; 0x3c 19c8: e3530000 cmp r3, #0 19cc: 1affffd1 bne 1918 19d0: e586a004 str sl, [r6, #4] 19d4: e1a04006 mov r4, r6 19d8: e5960008 ldr r0, [r6, #8] 19dc: ebfffffe bl 0 19e0: e24bd028 sub sp, fp, #40 ; 0x28 -- Kind regards, Minchan Kim -- 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/