The patch titled
Subject: zram: filter out recomp targets based on priority
has been added to the -mm mm-unstable branch. Its filename is
zram-filter-out-recomp-targets-based-on-priority.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/zram-filter-out-recomp-targets-based-on-priority.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: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Subject: zram: filter out recomp targets based on priority
Date: Fri, 14 Feb 2025 13:50:20 +0900
Do no select for post processing slots that are already compressed with
same or higher priority compression algorithm.
This should save some memory, as previously we would still put those
entries into corresponding post-processing buckets and filter them out
later in recompress_slot().
Link: https://lkml.kernel.org/r/20250214045208.1388854-9-senozhatsky@xxxxxxxxxxxx
Signed-off-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Cc: Hillf Danton <hdanton@xxxxxxxx>
Cc: Kairui Song <ryncsn@xxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Cc: Yosry Ahmed <yosry.ahmed@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/block/zram/zram_drv.c | 25 ++++++++++++++++---------
1 file changed, 16 insertions(+), 9 deletions(-)
--- a/drivers/block/zram/zram_drv.c~zram-filter-out-recomp-targets-based-on-priority
+++ a/drivers/block/zram/zram_drv.c
@@ -1864,7 +1864,7 @@ static int zram_bvec_write(struct zram *
#define RECOMPRESS_IDLE (1 << 0)
#define RECOMPRESS_HUGE (1 << 1)
-static int scan_slots_for_recompress(struct zram *zram, u32 mode,
+static int scan_slots_for_recompress(struct zram *zram, u32 mode, u32 prio_max,
struct zram_pp_ctl *ctl)
{
unsigned long nr_pages = zram->disksize >> PAGE_SHIFT;
@@ -1896,6 +1896,10 @@ static int scan_slots_for_recompress(str
zram_test_flag(zram, index, ZRAM_INCOMPRESSIBLE))
goto next;
+ /* Already compressed with same of higher priority */
+ if (zram_get_priority(zram, index) + 1 >= prio_max)
+ goto next;
+
pps->index = index;
place_pp_slot(zram, ctl, pps);
pps = NULL;
@@ -1952,6 +1956,16 @@ static int recompress_slot(struct zram *
zram_clear_flag(zram, index, ZRAM_IDLE);
class_index_old = zs_lookup_class_index(zram->mem_pool, comp_len_old);
+
+ prio = max(prio, zram_get_priority(zram, index) + 1);
+ /*
+ * Recompression slots scan should not select slots that are
+ * already compressed with a higher priority algorithm, but
+ * just in case
+ */
+ if (prio >= prio_max)
+ return 0;
+
/*
* Iterate the secondary comp algorithms list (in order of priority)
* and try to recompress the page.
@@ -1960,13 +1974,6 @@ static int recompress_slot(struct zram *
if (!zram->comps[prio])
continue;
- /*
- * Skip if the object is already re-compressed with a higher
- * priority algorithm (or same algorithm).
- */
- if (prio <= zram_get_priority(zram, index))
- continue;
-
num_recomps++;
zstrm = zcomp_stream_get(zram->comps[prio]);
src = kmap_local_page(page);
@@ -2191,7 +2198,7 @@ static ssize_t recompress_store(struct d
goto release_init_lock;
}
- scan_slots_for_recompress(zram, mode, ctl);
+ scan_slots_for_recompress(zram, mode, prio_max, ctl);
ret = len;
while ((pps = select_pp_slot(ctl))) {
_
Patches currently in -mm which might be from senozhatsky@xxxxxxxxxxxx are
zram-sleepable-entry-locking.patch
zram-permit-preemption-with-active-compression-stream.patch
zram-remove-unused-crypto-include.patch
zram-remove-max_comp_streams-device-attr.patch
zram-remove-two-staged-handle-allocation.patch
zram-remove-writestall-zram_stats-member.patch
zram-limit-max-recompress-prio-to-num_active_comps.patch
zram-filter-out-recomp-targets-based-on-priority.patch
zram-rework-recompression-loop.patch
zsmalloc-rename-pool-lock.patch
zsmalloc-make-zspage-lock-preemptible.patch
zsmalloc-introduce-new-object-mapping-api.patch
zram-switch-to-new-zsmalloc-object-mapping-api.patch
zram-permit-reclaim-in-zstd-custom-allocator.patch
zram-do-not-leak-page-on-recompress_store-error-path.patch
zram-do-not-leak-page-on-writeback_store-error-path.patch
zram-add-might_sleep-to-zcomp-api.patch
