Messages in this thread | | | Date | Fri, 29 Mar 2024 15:02:10 +0100 | 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 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.
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.
On the other hand, "same_filled_pages_enabled" sounds like some kind of a debugging option since I don't see any real reason to disable it either.
Thanks, Maciej
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