From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx152.postini.com [74.125.245.152]) by kanga.kvack.org (Postfix) with SMTP id DA4B86B0006 for ; Tue, 9 Apr 2013 19:28:46 -0400 (EDT) Received: from /spool/local by e33.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 9 Apr 2013 17:28:46 -0600 Received: from d03relay02.boulder.ibm.com (d03relay02.boulder.ibm.com [9.17.195.227]) by d03dlp02.boulder.ibm.com (Postfix) with ESMTP id 0147B3E40040 for ; Tue, 9 Apr 2013 17:28:28 -0600 (MDT) Received: from d03av01.boulder.ibm.com (d03av01.boulder.ibm.com [9.17.195.167]) by d03relay02.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r39NSes6164930 for ; Tue, 9 Apr 2013 17:28:40 -0600 Received: from d03av01.boulder.ibm.com (loopback [127.0.0.1]) by d03av01.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id r39NSeNk006627 for ; Tue, 9 Apr 2013 17:28:40 -0600 From: Cody P Schafer Subject: [PATCH v2 00/10] mm: fixup changers of per cpu pageset's ->high and ->batch Date: Tue, 9 Apr 2013 16:28:09 -0700 Message-Id: <1365550099-6795-1-git-send-email-cody@linux.vnet.ibm.com> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Gilad Ben-Yossef , Simon Jeons , KOSAKI Motohiro , Mel Gorman , Linux MM , LKML , Cody P Schafer "Problems" with the current code: 1. there is a lack of synchronization in setting ->high and ->batch in percpu_pagelist_fraction_sysctl_handler() 2. stop_machine() in zone_pcp_update() is unnecissary. 3. zone_pcp_update() does not consider the case where percpu_pagelist_fraction is non-zero To fix: 1. add memory barriers, a safe ->batch value, and an update side mutex when updating ->high and ->batch 2. avoid draining pages in zone_pcp_update(), rely upon the memory barriers added to fix #1 3. factor out quite a few functions, and then call the appropriate one. Note that it results in a change to the behavior of zone_pcp_update(), which is used by memory_hotplug. I'm rather certain that I've diserned (and preserved) the essential behavior (changing ->high and ->batch), and only eliminated unneeded actions (draining the per cpu pages), but this may not be the case. Further note that the draining of pages that previously took place in zone_pcp_update() occured after repeated draining when attempting to offline a page, and after the offline has "succeeded". It appears that the draining was added to zone_pcp_update() to avoid refactoring setup_pageset() into 2 funtions. -- Changes since v1: - instead of using on_each_cpu(), use memory barriers (Gilad) and an update side mutex. - add "Problem" #3 above, and fix. - rename function to match naming style of similar function - move unrelated comment Cody P Schafer (10): mm/page_alloc: factor out setting of pcp->high and pcp->batch. mm/page_alloc: prevent concurrent updaters of pcp ->batch and ->high mm/page_alloc: insert memory barriers to allow async update of pcp batch and high mm/page_alloc: convert zone_pcp_update() to rely on memory barriers instead of stop_machine() mm/page_alloc: when handling percpu_pagelist_fraction, don't unneedly recalulate high mm/page_alloc: factor setup_pageset() into pageset_init() and pageset_set_batch() mm/page_alloc: relocate comment to be directly above code it refers to. mm/page_alloc: factor zone_pageset_init() out of setup_zone_pageset() mm/page_alloc: in zone_pcp_update(), uze zone_pageset_init() mm/page_alloc: rename setup_pagelist_highmark() to match naming of pageset_set_batch() mm/page_alloc.c | 124 +++++++++++++++++++++++++++++++++----------------------- 1 file changed, 73 insertions(+), 51 deletions(-) -- 1.8.2 -- 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