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?
