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SubjectRe: [PATCH] mm/vmstats: add counters for the page frag cache
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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@lge.com>
> ---
> include/linux/vm_event_item.h | 4 ++++
> mm/page_alloc.c | 9 +++++++--
> mm/vmstat.c | 4 ++++
> 3 files changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
> index d77bc35..75425d4 100644
> --- a/include/linux/vm_event_item.h
> +++ b/include/linux/vm_event_item.h
> @@ -110,6 +110,10 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
> SWAP_RA,
> SWAP_RA_HIT,
> #endif
> + PGFRAG_ALLOC,
> + PGFRAG_FREE,
> + PGFRAG_ALLOC_CALLS,
> + PGFRAG_FREE_CALLS,
> NR_VM_EVENT_ITEMS
> };
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index db2d25f..b3ddd76 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -4322,6 +4322,7 @@ void __page_frag_cache_drain(struct page *page, unsigned int count)
> free_hot_cold_page(page, false);
> else
> __free_pages_ok(page, order);
> + __count_vm_events(PGFRAG_FREE, 1 << order);
> }
> }
> EXPORT_SYMBOL(__page_frag_cache_drain);
> @@ -4338,7 +4339,7 @@ void *page_frag_alloc(struct page_frag_cache *nc,
> page = __page_frag_cache_refill(nc, gfp_mask);
> if (!page)
> return NULL;
> -
> + __count_vm_events(PGFRAG_ALLOC, 1 << compound_order(page));
> #if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
> /* if size can vary use size else just use PAGE_SIZE */
> size = nc->size;
> @@ -4375,6 +4376,7 @@ void *page_frag_alloc(struct page_frag_cache *nc,
>
> nc->pagecnt_bias--;
> nc->offset = offset;
> + __count_vm_event(PGFRAG_ALLOC_CALLS);
>
> return nc->va + offset;
> }
> @@ -4387,8 +4389,11 @@ void page_frag_free(void *addr)
> {
> struct page *page = virt_to_head_page(addr);
>
> - if (unlikely(put_page_testzero(page)))
> + if (unlikely(put_page_testzero(page))) {
> + __count_vm_events(PGFRAG_FREE, 1 << compound_order(page));
> __free_pages_ok(page, compound_order(page));
> + }
> + __count_vm_event(PGFRAG_FREE_CALLS);
> }
> EXPORT_SYMBOL(page_frag_free);
>
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> index 4bb13e7..c00fe05 100644
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -1217,6 +1217,10 @@ const char * const vmstat_text[] = {
> "swap_ra",
> "swap_ra_hit",
> #endif
> + "pgfrag_alloc",
> + "pgfrag_free",
> + "pgfrag_alloc_calls",
> + "pgfrag_free_calls",
> #endif /* CONFIG_VM_EVENTS_COUNTERS */
> };
> #endif /* CONFIG_PROC_FS || CONFIG_SYSFS || CONFIG_NUMA */
>

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