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zram: split memory-tracking and ac-time tracking 

ZRAM_MEMORY_TRACKING enables two features:
- per-entry ac-time tracking
- debugfs interface

The latter one is the reason why memory-tracking depends on DEBUG_FS,
while the former one is used far beyond debugging these days.  Namely
ac-time is used for fine grained writeback of idle entries (pages).

Move ac-time tracking under its own config option so that it can be
enabled (along with writeback) on systems without DEBUG_FS.

[senozhatsky@chromium.org: ifdef fixup, per Dmytro]
  Link: https://lkml.kernel.org/r/20231117013543.540280-1-senozhatsky@chromium.org
Link: https://lkml.kernel.org/r/20231115024223.4133148-1-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Dmytro Maluka <dmaluka@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Sergey Senozhatsky 2023-11-15 11:42:12 +09:00 committed by Andrew Morton
parent 1b5c65b64c
commit a7a0350583
4 changed files with 25 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
Documentation/admin-guide/blockdev/zram.rst
View File

@ -328,7 +328,7 @@ as idle::
From now on, any pages on zram are idle pages. The idle mark
will be removed until someone requests access of the block.
IOW, unless there is access request, those pages are still idle pages.
Additionally, when CONFIG_ZRAM_MEMORY_TRACKING is enabled pages can be
Additionally, when CONFIG_ZRAM_TRACK_ENTRY_ACTIME is enabled pages can be
marked as idle based on how long (in seconds) it's been since they were
last accessed::

11
drivers/block/zram/Kconfig
View File

@ -69,9 +69,18 @@ config ZRAM_WRITEBACK
See Documentation/admin-guide/blockdev/zram.rst for more information.
config ZRAM_TRACK_ENTRY_ACTIME
bool "Track access time of zram entries"
depends on ZRAM
help
With this feature zram tracks access time of every stored
entry (page), which can be used for a more fine grained IDLE
pages writeback.
config ZRAM_MEMORY_TRACKING
bool "Track zRam block status"
depends on ZRAM && DEBUG_FS
select ZRAM_TRACK_ENTRY_ACTIME
help
With this feature, admin can track the state of allocated blocks
of zRAM. Admin could see the information via
@ -86,4 +95,4 @@ config ZRAM_MULTI_COMP
This will enable multi-compression streams, so that ZRAM can
re-compress pages using a potentially slower but more effective
compression algorithm. Note, that IDLE page recompression
requires ZRAM_MEMORY_TRACKING.
requires ZRAM_TRACK_ENTRY_ACTIME.

27
drivers/block/zram/zram_drv.c
View File

@ -174,6 +174,14 @@ static inline u32 zram_get_priority(struct zram *zram, u32 index)
return prio & ZRAM_COMP_PRIORITY_MASK;
}
static void zram_accessed(struct zram *zram, u32 index)
{
zram_clear_flag(zram, index, ZRAM_IDLE);
#ifdef CONFIG_ZRAM_TRACK_ENTRY_ACTIME
zram->table[index].ac_time = ktime_get_boottime();
#endif
}
static inline void update_used_max(struct zram *zram,
const unsigned long pages)
{
@ -293,8 +301,9 @@ static void mark_idle(struct zram *zram, ktime_t cutoff)
zram_slot_lock(zram, index);
if (zram_allocated(zram, index) &&
!zram_test_flag(zram, index, ZRAM_UNDER_WB)) {
#ifdef CONFIG_ZRAM_MEMORY_TRACKING
is_idle = !cutoff || ktime_after(cutoff, zram->table[index].ac_time);
#ifdef CONFIG_ZRAM_TRACK_ENTRY_ACTIME
is_idle = !cutoff || ktime_after(cutoff,
zram->table[index].ac_time);
#endif
if (is_idle)
zram_set_flag(zram, index, ZRAM_IDLE);
@ -317,7 +326,7 @@ static ssize_t idle_store(struct device *dev,
*/
u64 age_sec;
if (IS_ENABLED(CONFIG_ZRAM_MEMORY_TRACKING) && !kstrtoull(buf, 0, &age_sec))
if (IS_ENABLED(CONFIG_ZRAM_TRACK_ENTRY_ACTIME) && !kstrtoull(buf, 0, &age_sec))
cutoff_time = ktime_sub(ktime_get_boottime(),
ns_to_ktime(age_sec * NSEC_PER_SEC));
else
@ -841,12 +850,6 @@ static void zram_debugfs_destroy(void)
debugfs_remove_recursive(zram_debugfs_root);
}
static void zram_accessed(struct zram *zram, u32 index)
{
zram_clear_flag(zram, index, ZRAM_IDLE);
zram->table[index].ac_time = ktime_get_boottime();
}
static ssize_t read_block_state(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
@ -930,10 +933,6 @@ static void zram_debugfs_unregister(struct zram *zram)
#else
static void zram_debugfs_create(void) {};
static void zram_debugfs_destroy(void) {};
static void zram_accessed(struct zram *zram, u32 index)
{
zram_clear_flag(zram, index, ZRAM_IDLE);
};
static void zram_debugfs_register(struct zram *zram) {};
static void zram_debugfs_unregister(struct zram *zram) {};
#endif
@ -1254,7 +1253,7 @@ static void zram_free_page(struct zram *zram, size_t index)
{
unsigned long handle;
#ifdef CONFIG_ZRAM_MEMORY_TRACKING
#ifdef CONFIG_ZRAM_TRACK_ENTRY_ACTIME
zram->table[index].ac_time = 0;
#endif
if (zram_test_flag(zram, index, ZRAM_IDLE))

2
drivers/block/zram/zram_drv.h
View File

@ -69,7 +69,7 @@ struct zram_table_entry {
unsigned long element;
};
unsigned long flags;
#ifdef CONFIG_ZRAM_MEMORY_TRACKING
#ifdef CONFIG_ZRAM_TRACK_ENTRY_ACTIME
ktime_t ac_time;
#endif
};