Messages in this thread | | | Date | Mon, 13 Feb 2023 13:55:22 +0100 | Subject | Re: [PATCH v5 3/6] ksm: count all zero pages placed by KSM | From | David Hildenbrand <> |
| |
On 09.02.23 13:01, yang.yang29@zte.com.cn wrote: >>> diff --git a/mm/ksm.c b/mm/ksm.c >>> index 652c088f9786..72c0722be280 100644 >>> --- a/mm/ksm.c >>> +++ b/mm/ksm.c >>> @@ -276,6 +276,9 @@ static unsigned int zero_checksum __read_mostly; >>> /* Whether to merge empty (zeroed) pages with actual zero pages */ >>> static bool ksm_use_zero_pages __read_mostly; >>> >>> +/* The number of zero pages placed by KSM use_zero_pages */ >>> +static unsigned long ksm_zero_pages_sharing; >> >> Does this count how many zero pages are currently placed or how many >> rmap items with ZERO_PAGE_FLAG are in the system? > > Yes, it counts how many ksm zero pages are currently placed. and we use > rmap items with ZERO_PAGE_FLAG to record these zero page, similar to > ksm_pages_sharing and ksm_pages_shared which are recorded by the rmap_items > with STABLE_FLAG. > >> >> IOW, if someone triggers MADV_DONTNEED on such a zeropage, the counter >> will not get updated, correct? > > Well, the counter can get updated as someone triggers MADV_DONTNEED on such > a zeropage. You might write a simple code to test it.
Interesting, I'll have a look how that will be triggered.
-- Thanks,
David / dhildenb
| |