Messages in this thread |  | | From | Georgi Djakov <> | Subject | Re: [PATCH] mm/page_owner: Record timestamp and pid | Date | Fri, 27 Nov 2020 20:57:43 +0200 |
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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 */ > }; >
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