Messages in this thread | | | Date | Tue, 16 Jun 2015 22:19:03 +0900 | From | Minchan Kim <> | Subject | Re: [RFC][PATCHv2 2/8] zsmalloc: partial page ordering within a fullness_list |
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Hello Sergey,
On Fri, Jun 05, 2015 at 09:03:52PM +0900, Sergey Senozhatsky wrote: > We want to see more ZS_FULL pages and less ZS_ALMOST_{FULL, EMPTY} > pages. Put a page with higher ->inuse count first within its > ->fullness_list, which will give us better chances to fill up this > page with new objects (find_get_zspage() return ->fullness_list head > for new object allocation), so some zspages will become > ZS_ALMOST_FULL/ZS_FULL quicker. > > It performs a trivial and cheap ->inuse compare which does not slow > down zsmalloc, and in the worst case it keeps the list pages not in > any particular order, just like we do it now.
Fair enough.
I think it would be better with small cost and it matches current zsmalloc design which allocates a object from ALMOST_FULL zspage first to reduce memory footprint.
Although we uses page->lru to link zspages, it's not lru order so I like your idea.
One think I want to say is it doesn't need to be part of this patchset. I hope you gives some data to prove gain and includes it in changelog and resubmit, please.
> > A more expensive solution could sort fullness_list by ->inuse count. > > Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> > --- > mm/zsmalloc.c | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > > diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c > index ce3310c..cd37bda 100644 > --- a/mm/zsmalloc.c > +++ b/mm/zsmalloc.c > @@ -658,8 +658,16 @@ static void insert_zspage(struct page *page, struct size_class *class, > return; > > head = &class->fullness_list[fullness]; > - if (*head) > - list_add_tail(&page->lru, &(*head)->lru); > + if (*head) { > + /* > + * We want to see more ZS_FULL pages and less almost > + * empty/full. Put pages with higher ->inuse first. > + */ > + if (page->inuse < (*head)->inuse) > + list_add_tail(&page->lru, &(*head)->lru); > + else > + list_add(&page->lru, &(*head)->lru); > + } > > *head = page; > zs_stat_inc(class, fullness == ZS_ALMOST_EMPTY ? > -- > 2.4.2.387.gf86f31a >
-- Kind regards, Minchan Kim
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