On Mon, Apr 1, 2024 at 3:38 AM Maciej S. Szmigiero <mail@xxxxxxxxxxxxxxxxxxxxx> wrote: > > On 29.03.2024 19:22, Yosry Ahmed wrote: > > On Fri, Mar 29, 2024 at 10:45 AM Johannes Weiner <hannes@xxxxxxxxxxx> wrote: > >> > >> On Fri, Mar 29, 2024 at 03:02:10PM +0100, Maciej S. Szmigiero wrote: > >>> On 29.03.2024 03:14, Yosry Ahmed wrote: > >>>> On Thu, Mar 28, 2024 at 1:06 PM Yosry Ahmed <yosryahmed@xxxxxxxxxx> wrote: > >>>>> > >>>>> On Thu, Mar 28, 2024 at 12:11 PM Johannes Weiner <hannes@xxxxxxxxxxx> wrote: > >>>>>> > >>>>>> On Mon, Mar 25, 2024 at 11:50:13PM +0000, Yosry Ahmed wrote: > >>>>>>> There is no logical reason to refuse storing same-filled pages more > >>>>>>> efficiently and opt for compression. Remove the userspace knob. > >>>>>>> > >>>>>>> Signed-off-by: Yosry Ahmed <yosryahmed@xxxxxxxxxx> > >>>>>> > >>>>>> Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx> > >>>>>> > >>>>>> I also think the non_same_filled_pages_enabled option should go > >>>>>> away. Both of these tunables are pretty bizarre. > >>>>> > >>>>> Happy to remove both in the next version :) > >>>> > >>>> I thought non_same_filled_pages_enabled was introduced with the > >>>> initial support for same-filled pages, but it was introduced > >>>> separately (and much more recently): > >>>> https://lore.kernel.org/all/7dbafa963e8bab43608189abbe2067f4b9287831.1641247624.git.maciej.szmigiero@xxxxxxxxxx/ > >>>> > >>>> I am CCing Maciej to hear more about the use case for this. > >>> > >>> Thanks for CCing me. > >>> > >>> I introduced "non_same_filled_pages_enabled" a few years ago to > >>> enable using zswap in a lightweight mode where it is only used for > >>> its ability to store same-filled pages effectively. > >> > >> But all the pages it rejects go to disk swap instead, which is much > >> slower than compression... > >> > >>> As far as I remember, there were some interactions between full > >>> zswap and the cgroup memory controller - like, it made it easier > >>> for an aggressive workload to exceed its cgroup memory.high limits. > >> > >> Ok, that makes sense! A container fairness measure, rather than a > >> performance optimization. > >> > >> Fair enough, but that's moot then with cgroup accounting of the > >> backing memory, f4840ccfca25 ("zswap: memcg accounting"). > > > > Right, this should no longer be needed with the zswap charging. > > > > Maciej, is this still being used on kernels with f4840ccfca25 (5.19+)? > > Any objections to removing it now? > > I don't object to its removal as long as stable kernel trees aren't > affected. Yeah this isn't something that would be backported to stable kernels. Thanks for confirming.
