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Subject: Re: [PATCH] mm/page_owner: Record timestamp and pid
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        sudaraja@codeaurora.org, pratikp@codeaurora.org,
        lmark@codeaurora.org
References: <20201112184106.733-1-georgi.djakov@linaro.org>
 <20201112111436.c5deeadd3578877fc0b844a1@linux-foundation.org>
From:   Georgi Djakov <georgi.djakov@linaro.org>
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Message-ID: <0e3179bc-61ad-19e4-9b19-956609e44e75@linaro.org>
Date:   Fri, 13 Nov 2020 22:40:31 +0200
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On 11/12/20 21:14, Andrew Morton wrote:
> On Thu, 12 Nov 2020 20:41:06 +0200 Georgi Djakov <georgi.djakov@linaro.org> wrote:
> 
>> From: Liam Mark <lmark@codeaurora.org>
>>
>> Collect the time for each allocation recorded in page owner so that
>> allocation "surges" can be measured.
>>
>> Record the pid for each allocation recorded in page owner so that
>> the source of allocation "surges" can be better identified.
> 
> Please provide a description of why this is considered useful.  What
> has it been used for, what problems has it been used to solve?

Thanks for the quick feedback. I'll add more details in the commit message
when i post v2 next week.

> 
> Are there userspace tools which aid in the processing of this new
> information?

I'm not aware of any.

> 
> Can/should Documentation/vm/page_owner.rst be updated?

Yeah, probably i should update at least the size of the objects.

>> --- a/mm/page_owner.c
>> +++ b/mm/page_owner.c
>> @@ -10,6 +10,7 @@
>>  #include <linux/migrate.h>
>>  #include <linux/stackdepot.h>
>>  #include <linux/seq_file.h>
>> +#include <linux/sched/clock.h>
>>  
>>  #include "internal.h"
>>  
>> @@ -25,6 +26,8 @@ struct page_owner {
>>  	gfp_t gfp_mask;
>>  	depot_stack_handle_t handle;
>>  	depot_stack_handle_t free_handle;
>> +	u64 ts_nsec;
>> +	int pid;
> 
> pid_t would be nicer?

Yes, indeed! Thank you!

BR,
Georgi