linux-kernel - Re: [PATCH] memory-hotplug: add build zonelists when offline pages

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Message-ID: <50349FF7.6030407@cn.fujitsu.com>
Date:	Wed, 22 Aug 2012 17:01:43 +0800
From:	Wen Congyang <wency@...fujitsu.com>
To:	qiuxishi <qiuxishi@...il.com>
CC:	akpm@...ux-foundation.org, liuj97@...il.com,
	paul.gortmaker@...driver.com, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, bessel.wang@...wei.com,
	wujianguo@...wei.com, qiuxishi@...wei.com, jiang.liu@...wei.com,
	guohanjun@...wei.com, chenkeping@...wei.com, yinghai@...nel.org
Subject: Re: [PATCH] memory-hotplug: add build zonelists when offline pages

At 08/22/2012 03:59 PM, qiuxishi Wrote:
> On 2012-8-22 14:15, Wen Congyang wrote:
>> > At 08/21/2012 08:51 PM, qiuxishi Wrote:
>>> >> From: Xishi Qiu <qiuxishi@...wei.com>
>>> >>
>>> >> online_pages() does build_all_zonelists() and zone_pcp_update(),
>>> >> I think offline_pages() should do it too. The node has no memory
>>> >> to allocate, so remove this node's zones form other nodes' zonelists.
>>> >>
>>> >>
>>> >> Signed-off-by: Xishi Qiu <qiuxishi@...wei.com>
>>> >> ---
>>> >>  mm/memory_hotplug.c |    6 +++++-
>>> >>  1 files changed, 5 insertions(+), 1 deletions(-)
>>> >>
>>> >> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
>>> >> index bc7e7a2..5172bd4 100644
>>> >> --- a/mm/memory_hotplug.c
>>> >> +++ b/mm/memory_hotplug.c
>>> >> @@ -979,7 +979,11 @@ repeat:
>>> >>  	if (!node_present_pages(node)) {
>>> >>  		node_clear_state(node, N_HIGH_MEMORY);
>>> >>  		kswapd_stop(node);
>>> >> -	}
>>> >> +		mutex_lock(&zonelists_mutex);
>>> >> +		build_all_zonelists(NODE_DATA(node), NULL);
>> > 
>> > The node is still onlined now, so there is no need to pass
>> > this node's pgdat to build_all_zonelists().
>> > 
>> > I think we should build all zonelists when the zone has no
>> > pages.
>> > 
>>> >> +		mutex_unlock(&zonelists_mutex);
>>> >> +	} else
>>> >> +		zone_pcp_update(zone);
>> > 
>> > There is more than one zone in a node. So the zone can have
>> > no pages when the node has some pages.
>> > 
> Yes, you are right. Here is the new patch,

This version looks fine to me.

> 
> Signed-off-by: Xishi Qiu <qiuxishi@...wei.com>
> ---
>  mm/memory_hotplug.c |    7 ++++++-
>  1 files changed, 6 insertions(+), 1 deletions(-)
> 
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index bc7e7a2..5f6997f 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -973,8 +973,13 @@ repeat:
> 
>  	init_per_zone_wmark_min();
> 
> -	if (!populated_zone(zone))
> +	if (!populated_zone(zone)) {
>  		zone_pcp_reset(zone);
> +		mutex_lock(&zonelists_mutex);
> +		build_all_zonelists(NULL, NULL);
> +		mutex_unlock(&zonelists_mutex);
> +	} else
> +		zone_pcp_update(zone);
> 
>  	if (!node_present_pages(node)) {
>  		node_clear_state(node, N_HIGH_MEMORY);
> -- 1.7.6.1
>> > And we have called drain_all_pages(), I think there is no need
>> > to call zone_pcp_update() here.
>> > 
>> > Thanks
>> > Wen Congyang
>> > 
> In zone_pcp_update(), it calculates zone_batchsize() which does
> not calculated in drain_all_pages().

Yes, zone_batchsize() depends on zone's present pages.
If zone's present pages are changed, zone's pcp should be updated.

Thanks
Wen Congyang

> 
> Thanks
> Xishi Qiu
> 
>>> >>
>>> >>  	vm_total_pages = nr_free_pagecache_pages();
>>> >>  	writeback_set_ratelimit();
>> > 
>> > 
> --
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