On 13.04.2024 04:24, Yosry Ahmed wrote:
These knobs offer more fine-grained control to userspace than needed and
directly expose/influence kernel implementation; remove them.
For disabling same_filled handling, there is no logical reason to refuse
storing same-filled pages more efficiently and opt for compression.
Scanning pages for patterns may be an argument, but the page contents
will be read into the CPU cache anyway during compression. Also,
removing the same_filled handling code does not move the needle
significantly in terms of performance anyway [1].
For disabling non_same_filled handling, it was added when the compressed
pages in zswap were not being properly charged to memcgs, as workloads
could escape the accounting with compression [2]. This is no longer the
case after commit f4840ccfca25 ("zswap: memcg accounting"), and using
zswap without compression does not make much sense.
[1]https://lore.kernel.org/lkml/CAJD7tkaySFP2hBQw4pnZHJJwe3bMdjJ1t9VC2VJd=khn1_TXvA@xxxxxxxxxxxxxx/
[2]https://lore.kernel.org/lkml/19d5cdee-2868-41bd-83d5-6da75d72e940@xxxxxxxxxxxxxxxxxxxxx/
Cc: "Maciej S. Szmigiero" <mail@xxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Reviewed-by: Nhat Pham <nphamcs@xxxxxxxxx>
Reviewed-by: Chengming Zhou <chengming.zhou@xxxxxxxxx>
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I think you need to update zswap kernel docs, too.
Thanks,
Maciej
