On Wed, Jun 12, 2024 at 5:47 AM Usama Arif <usamaarif642@xxxxxxxxx> wrote: > > With an earlier commit to handle zero-filled pages in swap directly, > and with only 1% of the same-filled pages being non-zero, zswap no > longer needs to handle same-filled pages and can just work on compressed > pages. > > Signed-off-by: Usama Arif <usamaarif642@xxxxxxxxx> > --- > mm/zswap.c | 86 +++++------------------------------------------------- > 1 file changed, 8 insertions(+), 78 deletions(-) > > diff --git a/mm/zswap.c b/mm/zswap.c > index b9b35ef86d9b..ca8df9c99abf 100644 > --- a/mm/zswap.c > +++ b/mm/zswap.c > @@ -44,8 +44,6 @@ > **********************************/ > /* The number of compressed pages currently stored in zswap */ > atomic_t zswap_stored_pages = ATOMIC_INIT(0); > -/* The number of same-value filled pages currently stored in zswap */ > -static atomic_t zswap_same_filled_pages = ATOMIC_INIT(0); Can we re-introduce this counter somewhere? I have found this counter to be valuable in the past, and would love to keep it. For instance, in a system where a lot of zero-filled pages are reclaimed, we might see an increase in swap usage. Having this counter at hands will allow us to trace the source of the swap usage more easily. I *suppose* you can do elimination work (check zswap usage, check disk swap usage somehow - I'm not sure, etc., etc.), but this would be much more direct and user-friendly. Not *entirely* sure where to expose this though. Seems a bit specific for vmstat. Maybe as a new debugfs directory? This doesn't have to be done in this patch (or this series even) - but please consider this for follow-up work at least :)
