Messages in this thread | | | Subject | Re: [PATCH] mm/page_owner: Record timestamp and pid | From | Vlastimil Babka <> | Date | Fri, 27 Nov 2020 20:06:38 +0100 |
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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 :)
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 */ >> }; >> >
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