On 04.09.2017 04:35, Kyeongdon Kim wrote:
Thanks for your reply,
But I couldn't find "NR_FRAGMENT_PAGES" in linux-next.git .. is that vmstat counter? or others?
I mean rather than adding bunch vmstat counters for operations it might be
worth to add page counter which will show current amount of these pages.
But this seems too low-level for tracking, common counters for all network
buffers would be more useful but much harder to implement.
As I can see page owner is able to save stacktrace where allocation happened,
this makes debugging mostly trivial without any counters. If it adds too much
overhead - just track random 1% of pages, should be enough for finding leak.
As you know, page_frag_alloc() directly calls __alloc_pages_nodemask() function,
so that makes too difficult to see memory usage in real time even though we have "/meminfo or /slabinfo.." information.
If there was a way already to figure out the memory leakage from page_frag_cache in mainline, I agree your opinion
but I think we don't have it now.
If those counters too much in my patch,
I can say two values (pgfrag_alloc and pgfrag_free) are enough to guess what will happen
and would remove pgfrag_alloc_calls and pgfrag_free_calls.
Thanks,
Kyeongdon Kim
On 2017-09-01 오후 6:12, Konstantin Khlebnikov wrote:
IMHO that's too much counters.
Per-node NR_FRAGMENT_PAGES should be enough for guessing what's going on.
Perf probes provides enough features for furhter debugging.
On 01.09.2017 02:37, Kyeongdon Kim wrote:
> There was a memory leak problem when we did stressful test
> on Android device.
> The root cause of this was from page_frag_cache alloc
> and it was very hard to find out.
>
> We add to count the page frag allocation and free with function call.
> The gap between pgfrag_alloc and pgfrag_free is good to to calculate
> for the amount of page.
> The gap between pgfrag_alloc_calls and pgfrag_free_calls is for
> sub-indicator.
> They can see trends of memory usage during the test.
> Without it, it's difficult to check page frag usage so I believe we
> should add it.
>
> Signed-off-by: Kyeongdon Kim <kyeongdon.kim@xxxxxxx>
> ---
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