The patch titled
Subject: mm: zswap: remove same_filled module params
has been added to the -mm mm-unstable branch. Its filename is
mm-zswap-remove-same_filled-module-params.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-zswap-remove-same_filled-module-params.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
Subject: mm: zswap: remove same_filled module params
Date: Sat, 13 Apr 2024 02:24:07 +0000
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/
Link: https://lkml.kernel.org/r/20240413022407.785696-5-yosryahmed@xxxxxxxxxx
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>
Cc: "Maciej S. Szmigiero" <mail@xxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/zswap.c | 19 -------------------
1 file changed, 19 deletions(-)
--- a/mm/zswap.c~mm-zswap-remove-same_filled-module-params
+++ a/mm/zswap.c
@@ -123,19 +123,6 @@ static unsigned int zswap_accept_thr_per
module_param_named(accept_threshold_percent, zswap_accept_thr_percent,
uint, 0644);
-/*
- * Enable/disable handling same-value filled pages (enabled by default).
- * If disabled every page is considered non-same-value filled.
- */
-static bool zswap_same_filled_pages_enabled = true;
-module_param_named(same_filled_pages_enabled, zswap_same_filled_pages_enabled,
- bool, 0644);
-
-/* Enable/disable handling non-same-value filled pages (enabled by default) */
-static bool zswap_non_same_filled_pages_enabled = true;
-module_param_named(non_same_filled_pages_enabled, zswap_non_same_filled_pages_enabled,
- bool, 0644);
-
/* Number of zpools in zswap_pool (empirically determined for scalability) */
#define ZSWAP_NR_ZPOOLS 32
@@ -1386,9 +1373,6 @@ static bool zswap_is_folio_same_filled(s
unsigned int pos, last_pos = PAGE_SIZE / sizeof(*page) - 1;
bool ret = false;
- if (!zswap_same_filled_pages_enabled)
- return false;
-
page = kmap_local_folio(folio, 0);
val = page[0];
@@ -1466,9 +1450,6 @@ bool zswap_store(struct folio *folio)
goto store_entry;
}
- if (!zswap_non_same_filled_pages_enabled)
- goto freepage;
-
/* if entry is successfully added, it keeps the reference */
entry->pool = zswap_pool_current_get();
if (!entry->pool)
_
Patches currently in -mm which might be from yosryahmed@xxxxxxxxxx are
mm-memcg-add-null-check-to-obj_cgroup_put.patch
mm-zswap-remove-unnecessary-check-in-zswap_find_zpool.patch
percpu-clean-up-all-mappings-when-pcpu_map_pages-fails.patch
mm-zswap-remove-nr_zswap_stored-atomic.patch
mm-zswap-always-shrink-in-zswap_store-if-zswap_pool_reached_full.patch
mm-zswap-refactor-limit-checking-from-zswap_store.patch
mm-zswap-move-more-same-filled-pages-checks-outside-of-zswap_store.patch
mm-zswap-remove-same_filled-module-params.patch
mm-zswap-remove-same_filled-module-params-fix.patch
