linux-kernel - Re: [PATCH RFC] mm, proc: add PcpFree to meminfo

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Date:   Fri, 19 Aug 2022 09:06:45 +0800
From:   Kefeng Wang <wangkefeng.wang@...wei.com>
To:     Dave Hansen <dave.hansen@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        <linux-mm@...ck.org>, Aaron Lu <aaron.lu@...el.com>,
        Michal Hocko <mhocko@...e.com>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        "Vlastimil Babka" <vbabka@...e.cz>, Kemi Wang <kemi.wang@...el.com>
CC:     <linux-kernel@...r.kernel.org>, Liu Shixin <liushixin2@...wei.com>
Subject: Re: [PATCH RFC] mm, proc: add PcpFree to meminfo


On 2022/8/19 5:07, Dave Hansen wrote:
> On 8/17/22 00:16, Kefeng Wang wrote:
>> On 2022/8/16 16:44, Kefeng Wang wrote:
>>> From: Liu Shixin <liushixin2@...wei.com>
>>>
>>> The page on pcplist could be used, but not counted into memory free or
>>> avaliable, and pcp_free is only showed by show_mem(). Since commit
>>> d8a759b57035 ("mm, page_alloc: double zone's batchsize"), there is a
>>> significant decrease in the display of free memory, with a large number
>>> of cpus and nodes, the number of pages in the percpu list can be very
>>> large, so it is better to let user to know the pcp count.
>> Add more experts according to commit d8a759b57035，
>> any advice would be much appreciated，thanks.
> Adding a new meminfo field seems like overkill.  I'd just make this a
> part of MemFree if anything.
I like this way too.
> Also, some actual data would be nice here.  Like:
>
> 	Before commit d8a759b57035, the maximum amount of pages in the
> 	pcp lists was theoretically $FOO MB.  After the patch, the lists
> 	can hold $BAR MB.  It has been observed to be $BAZ MB in
> 	practice.
>
> 	This was all on a system with $X memory NUMA nodes and $Y CPUs.
>
> .

Same question in [1],  will repost with update, thanks.

[1] 
https://lore.kernel.org/linux-mm/03f465ca-cf8e-bbd1-1083-099fd2ce026d@huawei.com/t/#m50cf15911d9d203bd97238512fa2ae9ba1bd9e1e