Re: [PATCH 0/2] RFC: zswap tree use xarray instead of RB tree

[Chris Li]

On Thu, Jan 18, 2024 at 10:01 AM Nhat Pham <nphamcs@xxxxxxxxx> wrote:
>
> On Wed, Jan 17, 2024 at 7:06 PM Chris Li <chrisl@xxxxxxxxxx> wrote:
> >
> > The RB tree shows some contribution to the swap fault
> > long tail latency due to two factors:
> > 1) RB tree requires re-balance from time to time.
> > 2) The zswap RB tree has a tree level spin lock protecting
> > the tree access.
> >
> > The swap cache is using xarray. The break down the swap
> > cache access does not have the similar long time as zswap
> > RB tree.
> >
> > Moving the zswap entry to xarray enable read side
> > take read RCU lock only.
> >
> > The first patch adds the xarray alongside the RB tree.
> > There is some debug check asserting the xarray agrees with
> > the RB tree results.
> >
> > The second patch removes the zwap RB tree.
> >
> > I expect to merge the zswap rb tree spin lock with the xarray
> > lock in the follow up changes.
> >
> > I can surely use some help in reviewing and testing.
> >
> > Signed-off-by: Chris Li <chrisl@xxxxxxxxxx>
> > ---
> > Chris Li (2):
> >       mm: zswap.c: add xarray tree to zswap
>
> While I think it is pretty neat to keep the rbtree around to check if
> the results agree during development stages, in the final version
> please squash the patches. One patch is enough :)

Ack.

Chris