Messages in this thread | | | Date | Fri, 25 Mar 2022 21:19:51 +0100 | Subject | Re: [PATCH v3] mm/vmstat: add events for ksm cow | From | David Hildenbrand <> |
| |
On 25.03.22 21:09, Andrew Morton wrote: > On Thu, 24 Mar 2022 10:43:33 +0000 cgel.zte@gmail.com wrote: > >> From: Yang Yang <yang.yang29@zte.com.cn> >> >> Users may use ksm by calling madvise(, , MADV_MERGEABLE) when they want >> to save memory, it's a tradeoff by suffering delay on ksm cow. Users can >> get to know how much memory ksm saved by reading >> /sys/kernel/mm/ksm/pages_sharing, but they don't know what's the costs >> of ksm cow, and this is important of some delay sensitive tasks. >> >> So add ksm cow events to help users evaluate whether or how to use ksm. > > It's unclear (to me) how anyone will actually use this, how they will > interpret the output. > > Some tutorial words added to Documentation/vm/ksm.rst would be helpful. > While in there, please check for any other /proc/vmstat fields which > we forgot to document. > >> --- a/include/linux/vm_event_item.h >> +++ b/include/linux/vm_event_item.h >> @@ -131,6 +131,7 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT, >> SWAP_RA_HIT, >> #ifdef CONFIG_KSM >> KSM_SWPIN_COPY, >> + COW_KSM, > > I agree that this name looks unpleasingly backwards. Do we have an > expectation that we actually will be adding more COW_* fields?
As raised previously (also when proposing this), I'd like to have COW_ANON, COW_ZERO, COW_OTHER. Ideally, we'd have added all via a single patch for them. They would at least be of value to me.
-- Thanks,
David / dhildenb
| |