Messages in this thread | | | Date | Mon, 1 Apr 2024 12:37:56 +0200 | Subject | Re: [RFC PATCH 5/9] mm: zswap: remove zswap_same_filled_pages_enabled | From | "Maciej S. Szmigiero" <> |
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On 29.03.2024 19:22, Yosry Ahmed wrote: > On Fri, Mar 29, 2024 at 10:45 AM Johannes Weiner <hannes@cmpxchg.org> 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@google.com> wrote: >>>>> >>>>> On Thu, Mar 28, 2024 at 12:11 PM Johannes Weiner <hannes@cmpxchg.org> 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@google.com> >>>>>> >>>>>> Acked-by: Johannes Weiner <hannes@cmpxchg.org> >>>>>> >>>>>> 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@oracle.com/ >>>> >>>> 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.
Thanks, Maciej
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