From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx136.postini.com [74.125.245.136]) by kanga.kvack.org (Postfix) with SMTP id A59BB6B0070 for ; Wed, 24 Oct 2012 08:20:15 -0400 (EDT) Received: by mail-wg0-f71.google.com with SMTP id es5so353521wgb.2 for ; Wed, 24 Oct 2012 05:20:14 -0700 (PDT) Message-ID: <5087DCF8.6080205@ravellosystems.com> Date: Wed, 24 Oct 2012 14:20:08 +0200 From: Izik Eidus MIME-Version: 1.0 Subject: Re: ksm questions References: <5087CED1.2030307@gmail.com> <5087D50D.8000101@ravellosystems.com> <5087D817.7070106@gmail.com> <5087D8E3.6090900@ravellosystems.com> <5087DC00.6070408@gmail.com> In-Reply-To: <5087DC00.6070408@gmail.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Ni zhan Chen Cc: Linux Memory Management List , Andrea Arcangeli , Petr Holasek , Hugh Dickins , Chris Wright , Rik van Riel On 10/24/2012 02:16 PM, Ni zhan Chen wrote: > On 10/24/2012 08:02 PM, Izik Eidus wrote: >> On 10/24/2012 01:59 PM, Ni zhan Chen wrote: >>> On 10/24/2012 07:46 PM, Izik Eidus wrote: >>>> On 10/24/2012 01:19 PM, Ni zhan Chen wrote: >>>>> Hi all, >>>>> >>>>> I have some questions about ksm. >>>>> >>>>> 1) khugepaged default nice value is 19, but ksmd default nice >>>>> value is 5, why this big different? >>>>> 2) why ksm doesn't support pagecache and tmpfs now? What's the >>>>> bottleneck? >>>>> 3) ksm kernel doc said that "KSM only merges anonymous(private) >>>>> pages, never pagecache(file) pages". But where judege it should be >>>>> private? >>>>> 4) ksm kernel doc said that "To avoid the instability and the >>>>> resulting false negatives to be permanent, KSM re-initializes the >>>>> unstable tree root node to an empty tree, at every KSM pass." But >>>>> I can't find where re-initializes the unstable tree, could you >>>>> explain me? >>>> >>>> >>>> in scan_get_next_rmap_item(), if (slot == &ksm_mm_head) then we do >>>> root_unstable_tree = RB_ROOT; this will result in >>>> root_unstable_tree being empty. >>> >>> thanks Izik, what about the other three questions? >> >> Question number 2 is beacuse it is forced to work with anonymous >> pages, about question 3 - I will have to remember why from the very >> begining I wrote it to support only anonymous pages (few years have >> been passed), maybe Andrea/Huge have it more hot in their heads? > > The initialize goal of design ksm is for virtualization, but now it > also can be used for other apps. So can it also support tmpfs or > pagecache in the future? Talking from far memory, I remember it was easier/cleaner to only support anonymous pages, until Andrea/Huge won`t remind us why I can`t answer this (Maybe later I will have some time to read a little bit the code again and to remember what is going on in linux VM...) > >> >>> >>>> >>>>> >>>>> Thanks in advance. :-) >>>>> >>>>> Regards, >>>>> Chen >>>>> >>>> >>>> >>> >> >> > -- 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