The patch titled
Subject: zram: mark incompressible page as ZRAM_HUGE
has been added to the -mm tree. Its filename is
zram-mark-incompressible-page-as-zram_huge.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/zram-mark-incompressible-page-as-zram_huge.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/zram-mark-incompressible-page-as-zram_huge.patch
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------------------------------------------------------
From: Minchan Kim <minchan@xxxxxxxxxx>
Subject: zram: mark incompressible page as ZRAM_HUGE
Mark incompressible pages so that we could investigate who is the owner of
the incompressible pages once the page is swapped out via using upcoming
zram memory tracker feature.
With it, we could prevent such pages to be swapped out by using mlock.
Otherwise we might remove them.
This patch exposes new stat for huge pages via mm_stat.
Link: http://lkml.kernel.org/r/20180416090946.63057-3-minchan@xxxxxxxxxx
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/blockdev/zram.txt | 1 +
drivers/block/zram/zram_drv.c | 17 ++++++++++++++---
drivers/block/zram/zram_drv.h | 2 ++
3 files changed, 17 insertions(+), 3 deletions(-)
diff -puN Documentation/blockdev/zram.txt~zram-mark-incompressible-page-as-zram_huge Documentation/blockdev/zram.txt
--- a/Documentation/blockdev/zram.txt~zram-mark-incompressible-page-as-zram_huge
+++ a/Documentation/blockdev/zram.txt
@@ -218,6 +218,7 @@ line of text and contains the following
same_pages the number of same element filled pages written to this disk.
No memory is allocated for such pages.
pages_compacted the number of pages freed during compaction
+ huge_pages the number of incompressible pages
9) Deactivate:
swapoff /dev/zram0
diff -puN drivers/block/zram/zram_drv.c~zram-mark-incompressible-page-as-zram_huge drivers/block/zram/zram_drv.c
--- a/drivers/block/zram/zram_drv.c~zram-mark-incompressible-page-as-zram_huge
+++ a/drivers/block/zram/zram_drv.c
@@ -729,14 +729,15 @@ static ssize_t mm_stat_show(struct devic
max_used = atomic_long_read(&zram->stats.max_used_pages);
ret = scnprintf(buf, PAGE_SIZE,
- "%8llu %8llu %8llu %8lu %8ld %8llu %8lu\n",
+ "%8llu %8llu %8llu %8lu %8ld %8llu %8lu %8llu\n",
orig_size << PAGE_SHIFT,
(u64)atomic64_read(&zram->stats.compr_data_size),
mem_used << PAGE_SHIFT,
zram->limit_pages << PAGE_SHIFT,
max_used << PAGE_SHIFT,
(u64)atomic64_read(&zram->stats.same_pages),
- pool_stats.pages_compacted);
+ pool_stats.pages_compacted,
+ (u64)atomic64_read(&zram->stats.huge_pages));
up_read(&zram->init_lock);
return ret;
@@ -805,6 +806,11 @@ static void zram_free_page(struct zram *
{
unsigned long handle;
+ if (zram_test_flag(zram, index, ZRAM_HUGE)) {
+ zram_clear_flag(zram, index, ZRAM_HUGE);
+ atomic64_dec(&zram->stats.huge_pages);
+ }
+
if (zram_wb_enabled(zram) && zram_test_flag(zram, index, ZRAM_WB)) {
zram_wb_clear(zram, index);
atomic64_dec(&zram->stats.pages_stored);
@@ -973,6 +979,7 @@ compress_again:
}
if (unlikely(comp_len >= huge_class_size)) {
+ comp_len = PAGE_SIZE;
if (zram_wb_enabled(zram) && allow_wb) {
zcomp_stream_put(zram->comp);
ret = write_to_bdev(zram, bvec, index, bio, &element);
@@ -984,7 +991,6 @@ compress_again:
allow_wb = false;
goto compress_again;
}
- comp_len = PAGE_SIZE;
}
/*
@@ -1046,6 +1052,11 @@ out:
zram_slot_lock(zram, index);
zram_free_page(zram, index);
+ if (comp_len == PAGE_SIZE) {
+ zram_set_flag(zram, index, ZRAM_HUGE);
+ atomic64_inc(&zram->stats.huge_pages);
+ }
+
if (flags) {
zram_set_flag(zram, index, flags);
zram_set_element(zram, index, element);
diff -puN drivers/block/zram/zram_drv.h~zram-mark-incompressible-page-as-zram_huge drivers/block/zram/zram_drv.h
--- a/drivers/block/zram/zram_drv.h~zram-mark-incompressible-page-as-zram_huge
+++ a/drivers/block/zram/zram_drv.h
@@ -47,6 +47,7 @@ enum zram_pageflags {
ZRAM_LOCK = ZRAM_FLAG_SHIFT,
ZRAM_SAME, /* Page consists the same element */
ZRAM_WB, /* page is stored on backing_device */
+ ZRAM_HUGE, /* Incompressible page */
__NR_ZRAM_PAGEFLAGS,
};
@@ -71,6 +72,7 @@ struct zram_stats {
atomic64_t invalid_io; /* non-page-aligned I/O requests */
atomic64_t notify_free; /* no. of swap slot free notifications */
atomic64_t same_pages; /* no. of same element filled pages */
+ atomic64_t huge_pages; /* no. of huge pages */
atomic64_t pages_stored; /* no. of pages currently stored */
atomic_long_t max_used_pages; /* no. of maximum pages stored */
atomic64_t writestall; /* no. of write slow paths */
_
Patches currently in -mm which might be from minchan@xxxxxxxxxx are
zram-correct-flag-name-of-zram_access.patch
zram-mark-incompressible-page-as-zram_huge.patch
zram-record-accessed-second.patch
zram-introduce-zram-memory-tracking.patch
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