From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f180.google.com (mail-pd0-f180.google.com [209.85.192.180]) by kanga.kvack.org (Postfix) with ESMTP id 8651B6B0038 for ; Fri, 26 Sep 2014 04:52:29 -0400 (EDT) Received: by mail-pd0-f180.google.com with SMTP id r10so12587204pdi.39 for ; Fri, 26 Sep 2014 01:52:29 -0700 (PDT) Received: from BAY004-OMC2S26.hotmail.com (bay004-omc2s26.hotmail.com. [65.54.190.101]) by mx.google.com with ESMTPS id kn10si1977067pbd.49.2014.09.26.01.52.28 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Fri, 26 Sep 2014 01:52:28 -0700 (PDT) Message-ID: From: Pintu Kumar Subject: Changing PAGE_ALLOC_COSTLY_ORDER from 3 to 2 Date: Fri, 26 Sep 2014 14:22:27 +0530 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: "mgorman@suse.de" , "linaro-mm-sig@lists.linaro.org" , "linux-arm-kernel@lists.infradead.org" , "linux-mm@kvack.org" , PINTU KUMAR , "pintu.k@samsung.com" , "linux-kernel@vger.kernel.org" Hi=2C=0A= =0A= I wanted to know about the impact of changing PAGE_ALLOC_COSTLY_ORDER value= from 3 to 2.=0A= This macro is defined in include/linux/mmzone.h=0A= #define PAGE_ALLOC_COSTLY_ORDER=A0=A0 3=0A= =0A= As I know this value should never be changed irrespective of the type of th= e system.=0A= Is it good to change this value for RAM size: 512MB=2C 256MB or 128MB?=0A= If anybody have changed this value and experience any kind of problem or be= nefits please let us know.=0A= =0A= We noticed that for one of the Android product with 512MB RAM=2C the PAGE_A= LLOC_COSTLY_ORDER was set to 2.=0A= We could not figure out why this value was decreased from 3 to 2.=0A= =0A= As per my analysis=2C I observed that kmalloc fails little early=2C if we c= hange this value to 2.=0A= This is also visible from the _slowpath_ in page_alloc.c=0A= =0A= Apart from this we could not find any other impact.=0A= If anybody is aware of any other impact=2C please let us know.=0A= =0A= =0A= =0A= Thank you!=0A= Regards=2C=0A= Pintu Kumar=0A= =0A= = -- 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