From: Georgi Djakov <georgi.djakov@linaro.org>
To: Vlastimil Babka <vbabka@suse.cz>,
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
Subject: Re: [PATCH] mm/page_owner: Record timestamp and pid
Date: Fri, 27 Nov 2020 20:57:43 +0200 [thread overview]
Message-ID: <3ef3d770-d74b-5588-6672-f092c1526461@linaro.org> (raw)
In-Reply-To: <02f682e2-0e9b-76a8-04fa-487891e18bdf@suse.cz>
Hi Vlastimil,
Thanks for the comment!
On 11/27/20 19:52, Vlastimil Babka wrote:
> On 11/12/20 8:14 PM, 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?
>
> Worth noting that on x86_64 it doubles the size of struct page_owner
> from 16 bytes to 32, so it better be justified:
Well, that's true. But for debug options there is almost always some penalty.
The timestamp and pid information is very useful for me (and others, i believe)
when doing memory analysis. On a crash for example, we can get this information
from kdump (or RAM-dump) and look into it to catch memory allocation problems
more easily.
If you find the above argument not strong enough, how about a separate config
option for this? Maybe something like CONFIG_PAGE_OWNER_EXTENDED, which could
be enabled in addition to CONFIG_PAGE_OWNER?
Thanks,
Georgi
>
> struct page_owner {
> short unsigned int order; /* 0 2 */
> short int last_migrate_reason; /* 2 2 */
> gfp_t gfp_mask; /* 4 4 */
> depot_stack_handle_t handle; /* 8 4 */
> depot_stack_handle_t free_handle; /* 12 4 */
> u64 ts_nsec; /* 16 8 */
> int pid; /* 24 4 */
>
> /* size: 32, cachelines: 1, members: 7 */
> /* padding: 4 */
> /* last cacheline: 32 bytes */
> };
>
next prev parent reply other threads:[~2020-11-27 19:00 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-12 18:41 [PATCH] mm/page_owner: Record timestamp and pid Georgi Djakov
2020-11-12 19:14 ` Andrew Morton
2020-11-13 20:40 ` Georgi Djakov
2020-11-27 17:52 ` Vlastimil Babka
2020-11-27 18:57 ` Georgi Djakov [this message]
2020-11-27 19:06 ` Vlastimil Babka
2020-11-27 19:23 ` Souptick Joarder
2020-11-30 12:04 ` Vlastimil Babka
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