From: Souptick Joarder <jrdr.linux@gmail.com>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Georgi Djakov <georgi.djakov@linaro.org>,
Andrew Morton <akpm@linux-foundation.org>,
Linux-MM <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: Sat, 28 Nov 2020 00:53:11 +0530 [thread overview]
Message-ID: <CAFqt6zaZ8NCUUMpXA_-r2D-c_J99yrhjfRrpPFYhcebASeHebw@mail.gmail.com> (raw)
In-Reply-To: <bdf8727f-1191-34bd-d8ec-69b2a3d50c1b@suse.cz>
On Sat, Nov 28, 2020 at 12:36 AM Vlastimil Babka <vbabka@suse.cz> wrote:
>
> On 11/27/20 7:57 PM, Georgi Djakov wrote:
> > 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.
>
> Right. Btw, you should add printing the info to __dump_page_owner().
>
> > 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?
>
> It might be strong enough if it's mentioned in changelog, and also what exactly
> the space tradeoff is :)
Just a thought ... putting it inside CONFIG_PAGE_OWNER_DEBUG might be
better if it is used
purely for debugging purposes.
>
> You can also mention that SLUB object tracking has also pid+timestamp.
>
> > 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:[~2020-11-28 18:03 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
2020-11-27 19:06 ` Vlastimil Babka
2020-11-27 19:23 ` Souptick Joarder [this message]
2020-11-30 12:04 ` Vlastimil Babka
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