linux-kernel - Re: [PATCH] mm: fix the inaccurate memory statistics issue for users

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Message-ID: <a5319627-c32e-46de-8616-39fbbd2d369e@suse.cz>
Date: Wed, 4 Jun 2025 16:27:18 +0200
From: Vlastimil Babka <vbabka@...e.cz>
To: Baolin Wang <baolin.wang@...ux.alibaba.com>,
 Shakeel Butt <shakeel.butt@...ux.dev>, Michal Hocko <mhocko@...e.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>, david@...hat.com,
 lorenzo.stoakes@...cle.com, Liam.Howlett@...cle.com, rppt@...nel.org,
 surenb@...gle.com, donettom@...ux.ibm.com, aboorvad@...ux.ibm.com,
 sj@...nel.org, linux-mm@...ck.org, linux-fsdevel@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: fix the inaccurate memory statistics issue for users

On 6/4/25 16:16, Baolin Wang wrote:
>>>
>>> # Get the PIDs of stress-ng processes
>>> PIDS=$(pgrep stress-ng)
>>>
>>> # Loop through each PID and monitor /proc/[pid]/status
>>> for PID in $PIDS; do
>>>       while true; do
>>>           cat /proc/$PID/status
>>> 	usleep 100000
>> 
>> Hm but this limits the reading to 10 per second? If we want to simulate an
>> adversary process, it should be without the sleeps I think?
> 
> OK. I drop the usleep, and I still can not see obvious impact.

Thanks, that's reassuring.

> w/o patch:
> stress-ng: info:  [6848]          4,399,219,085,152 CPU Cycles 
>           67.327 B/sec
> stress-ng: info:  [6848]          1,616,524,844,832 Instructions 
>           24.740 B/sec (0.367 instr. per cycle)
> stress-ng: info:  [6848]                 39,529,792 Page Faults Total 
>            0.605 M/sec
> stress-ng: info:  [6848]                 39,529,792 Page Faults Minor 
>            0.605 M/sec
> 
> w/patch:
> stress-ng: info:  [2485]          4,462,440,381,856 CPU Cycles 
>           68.382 B/sec
> stress-ng: info:  [2485]          1,615,101,503,296 Instructions 
>           24.750 B/sec (0.362 instr. per cycle)
> stress-ng: info:  [2485]                 39,439,232 Page Faults Total 
>            0.604 M/sec
> stress-ng: info:  [2485]                 39,439,232 Page Faults Minor 
>            0.604 M/sec