On (22/11/03 12:45), Johannes Weiner wrote:
> On Wed, Nov 02, 2022 at 01:13:58PM +0900, Sergey Senozhatsky wrote:
> > On (22/10/27 11:27), Nhat Pham wrote:
> > > +
> > > +static int zs_zpool_shrink(void *pool, unsigned int pages,
> > > + unsigned int *reclaimed)
> > > +{
> > > + unsigned int total = 0;
> > > + int ret = -EINVAL;
> > > +
> > > + while (total < pages) {
> > > + ret = zs_reclaim_page(pool, 8);
> > > + if (ret < 0)
> > > + break;
> > > + total++;
> > > + }
> > > +
> > > + if (reclaimed)
> > > + *reclaimed = total;
> > > +
> > > + return ret;
> > > +}
> >
> > The name collides with shrinker callbacks (compaction). That's a bit
> > confusing, took me some time.
>
> Yeah this tripped us up too.
>
> Unfortunately, this is inherited from the zpool API:
Yeah, sure. I don't ask to rename zpool API, that was just a personal
note that it took me sometime to figure out that now we have two different
shrinkers.
> > > @@ -482,6 +504,7 @@ static struct zpool_driver zs_zpool_driver = {
> > > .malloc_support_movable = true,
> > > .malloc = zs_zpool_malloc,
> > > .free = zs_zpool_free,
> > > + .shrink = zs_zpool_shrink,
>
> There is another terminology collision around "compaction" and
> "migration": There is zs_page_migrate() which is called from physical
> page migration and compaction to switch out backing struct pages of
> the zspage. Then there is migrate_zspage() which is called from a
> *shrinker* through *zs_compact()*, and it consolidates the objects
> from partially used zspages into full ones.
Oh, yeah...
> We're collecting these issues and want to clean them up separately. It
> seems this codebase hasn't had a lot of TLC recently, which makes it
> harder to make needed changes :/ We try to clean up as we go, but some
> of these issues (like the .shrink callback) run through all backends,
> zpool and zswap, so they'd be better off in separate cleanup patches.
Totally agreed with the separate effort/patches.
