The patch titled
Subject: zram: add algo parameter support to zram_recompress()
has been added to the -mm mm-unstable branch. Its filename is
zram-add-algo-parameter-support-to-zram_recompress.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/zram-add-algo-parameter-support-to-zram_recompress.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Subject: zram: add algo parameter support to zram_recompress()
Date: Wed, 9 Nov 2022 20:50:44 +0900
Recompression iterates through all the registered secondary compression
algorithms in order of their priorities so that we have higher chances of
finding the algorithm that compresses a particular page. This, however,
may not always be best approach and sometimes we may want to limit
recompression to only one particular algorithm. For instance, when a
higher priority algorithm uses too much power and device has a relatively
low battery level we may want to limit recompression to use only a lower
priority algorithm, which uses less power.
Introduce algo= parameter support to recompression sysfs knob so that
user-sapce can request recompression with particular algorithm only:
echo "type=idle algo=zstd" > /sys/block/zramX/recompress
Link: https://lkml.kernel.org/r/20221109115047.2921851-11-senozhatsky@xxxxxxxxxxxx
Signed-off-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Acked-by: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Alexey Romanov <avromanov@xxxxxxxxxxxxxx>
Cc: Nhat Pham <nphamcs@xxxxxxxxx>
Cc: Nitin Gupta <ngupta@xxxxxxxxxx>
Cc: Suleiman Souhlal <suleiman@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/block/zram/zram_drv.c | 54 ++++++++++++++++++++++++++------
drivers/block/zram/zram_drv.h | 1
2 files changed, 46 insertions(+), 9 deletions(-)
--- a/drivers/block/zram/zram_drv.c~zram-add-algo-parameter-support-to-zram_recompress
+++ a/drivers/block/zram/zram_drv.c
@@ -1674,6 +1674,7 @@ static int zram_recompress(struct zram *
unsigned int comp_len_new;
unsigned int class_index_old;
unsigned int class_index_new;
+ u32 num_recomps = 0;
void *src, *dst;
int ret;
@@ -1708,6 +1709,7 @@ static int zram_recompress(struct zram *
if (prio <= zram_get_priority(zram, index))
continue;
+ num_recomps++;
zstrm = zcomp_stream_get(zram->comps[prio]);
src = kmap_atomic(page);
ret = zcomp_compress(zstrm, src, &comp_len_new);
@@ -1740,13 +1742,19 @@ static int zram_recompress(struct zram *
if (!zstrm)
return 0;
- /*
- * All secondary algorithms failed to re-compress the page in a way
- * that would save memory, mark the object as incompressible so that
- * we will not try to compress it again.
- */
if (class_index_new >= class_index_old) {
- zram_set_flag(zram, index, ZRAM_INCOMPRESSIBLE);
+ /*
+ * Secondary algorithms failed to re-compress the page
+ * in a way that would save memory, mark the object as
+ * incompressible so that we will not try to compress
+ * it again.
+ *
+ * We need to make sure that all secondary algorithms have
+ * failed, so we test if the number of recompressions matches
+ * the number of active secondary algorithms.
+ */
+ if (num_recomps == zram->num_active_comps - 1)
+ zram_set_flag(zram, index, ZRAM_INCOMPRESSIBLE);
return 0;
}
@@ -1795,10 +1803,11 @@ static ssize_t recompress_store(struct d
struct device_attribute *attr,
const char *buf, size_t len)
{
+ u32 prio = ZRAM_SECONDARY_COMP, prio_max = ZRAM_MAX_COMPS;
struct zram *zram = dev_to_zram(dev);
- u32 mode = 0, threshold = 0, prio = ZRAM_SECONDARY_COMP;
unsigned long nr_pages = zram->disksize >> PAGE_SHIFT;
- char *args, *param, *val;
+ char *args, *param, *val, *algo = NULL;
+ u32 mode = 0, threshold = 0;
unsigned long index;
struct page *page;
ssize_t ret;
@@ -1830,6 +1839,11 @@ static ssize_t recompress_store(struct d
return ret;
continue;
}
+
+ if (!strcmp(param, "algo")) {
+ algo = val;
+ continue;
+ }
}
if (threshold >= PAGE_SIZE)
@@ -1841,6 +1855,26 @@ static ssize_t recompress_store(struct d
goto release_init_lock;
}
+ if (algo) {
+ bool found = false;
+
+ for (; prio < ZRAM_MAX_COMPS; prio++) {
+ if (!zram->comp_algs[prio])
+ continue;
+
+ if (!strcmp(zram->comp_algs[prio], algo)) {
+ prio_max = min(prio + 1, ZRAM_MAX_COMPS);
+ found = true;
+ break;
+ }
+ }
+
+ if (!found) {
+ ret = -EINVAL;
+ goto release_init_lock;
+ }
+ }
+
page = alloc_page(GFP_KERNEL);
if (!page) {
ret = -ENOMEM;
@@ -1871,7 +1905,7 @@ static ssize_t recompress_store(struct d
goto next;
err = zram_recompress(zram, index, page, threshold,
- prio, ZRAM_MAX_COMPS);
+ prio, prio_max);
next:
zram_slot_unlock(zram, index);
if (err) {
@@ -2107,6 +2141,7 @@ static void zram_destroy_comps(struct zr
if (!comp)
continue;
zcomp_destroy(comp);
+ zram->num_active_comps--;
}
}
@@ -2174,6 +2209,7 @@ static ssize_t disksize_store(struct dev
}
zram->comps[prio] = comp;
+ zram->num_active_comps++;
}
zram->disksize = disksize;
set_capacity_and_notify(zram->disk, zram->disksize >> SECTOR_SHIFT);
--- a/drivers/block/zram/zram_drv.h~zram-add-algo-parameter-support-to-zram_recompress
+++ a/drivers/block/zram/zram_drv.h
@@ -125,6 +125,7 @@ struct zram {
*/
u64 disksize; /* bytes */
const char *comp_algs[ZRAM_MAX_COMPS];
+ s8 num_active_comps;
/*
* zram is claimed so open request will be failed
*/
_
Patches currently in -mm which might be from senozhatsky@xxxxxxxxxxxx are
zram-preparation-for-multi-zcomp-support.patch
zram-add-recompression-algorithm-sysfs-knob.patch
zram-factor-out-wb-and-non-wb-zram-read-functions.patch
zram-introduce-recompress-sysfs-knob.patch
zram-add-recompress-flag-to-read_block_state.patch
zram-clarify-writeback_store-comment.patch
zram-use-is_err_value-to-check-for-zs_malloc-errors.patch
zram-remove-redundant-checks-from-zram_recompress.patch
zram-add-algo-parameter-support-to-zram_recompress.patch
documentation-add-zram-recompression-documentation.patch
zram-add-incompressible-writeback.patch
zram-add-incompressible-flag-to-read_block_state.patch
