Re: [PATCH 1/6] tracing, page-allocator: Add trace events for page allocation and page freeing

[KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>]

2009/8/8 Mel Gorman <mel@csn.ul.ie>:
> This patch adds trace events for the allocation and freeing of pages,
> including the freeing of pagevecs.  Using the events, it will be known what
> struct page and pfns are being allocated and freed and what the call site
> was in many cases.
>
> The page alloc tracepoints be used as an indicator as to whether the workload
> was heavily dependant on the page allocator or not. You can make a guess based
> on vmstat but you can't get a per-process breakdown. Depending on the call
> path, the call_site for page allocation may be __get_free_pages() instead
> of a useful callsite. Instead of passing down a return address similar to
> slab debugging, the user should enable the stacktrace and seg-addr options
> to get a proper stack trace.
>
> The pagevec free tracepoint has a different usecase. It can be used to get
> a idea of how many pages are being dumped off the LRU and whether it is
> kswapd doing the work or a process doing direct reclaim.
>
> Signed-off-by: Mel Gorman <mel@csn.ul.ie>
> Acked-by: Rik van Riel <riel@redhat.com>

Looks good to me.
  Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>

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