Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <af1ee19f-c4fe-ee80-ec4c-b3d3a859795b@huawei.com>
Date:   Fri, 19 Aug 2022 09:06:45 +0800
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101
 Thunderbird/91.9.1
Subject: Re: [PATCH RFC] mm, proc: add PcpFree to meminfo
Content-Language: en-US
To:     Dave Hansen <dave.hansen@intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        <linux-mm@kvack.org>, Aaron Lu <aaron.lu@intel.com>,
        Michal Hocko <mhocko@suse.com>,
        Jesper Dangaard Brouer <brouer@redhat.com>,
        "Vlastimil Babka" <vbabka@suse.cz>, Kemi Wang <kemi.wang@intel.com>
CC:     <linux-kernel@vger.kernel.org>, Liu Shixin <liushixin2@huawei.com>
References: <20220816084426.135528-1-wangkefeng.wang@huawei.com>
 <99556483-9f22-4597-8270-b4414cc97e64@huawei.com>
 <19144f97-2b00-fed6-5395-0221bbc60802@intel.com>
From:   Kefeng Wang <wangkefeng.wang@huawei.com>
In-Reply-To: <19144f97-2b00-fed6-5395-0221bbc60802@intel.com>
Content-Type: text/plain; charset="UTF-8"; format=flowed
Content-Transfer-Encoding: 8bit
Precedence: bulk


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@huawei.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