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

From: Kefeng Wang
Date: Thu Aug 18 2022 - 21:06:53 EST



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@xxxxxxxxxx>

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@xxxxxxxxxx/t/#m50cf15911d9d203bd97238512fa2ae9ba1bd9e1e