| Message ID | 20210924161128.1508015-1-bgeffon@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v5] zram: Introduce an aged idle interface | expand |
On Fri, 24 Sep 2021 09:11:28 -0700 Brian Geffon <bgeffon@google.com> wrote: > This change introduces an aged idle interface to the existing > idle sysfs file for zram. > > When CONFIG_ZRAM_MEMORY_TRACKING is enabled the idle file > now also accepts an integer argument. This integer is the > age (in seconds) of pages to mark as idle. The idle file > still supports 'all' as it always has. This new approach > allows for much more control over which pages get marked > as idle. > > v4 -> v5: > - Andrew's suggestions to use IS_ENABLED and > cleanup comment. Also this? --- a/drivers/block/zram/zram_drv.c~zram-introduce-an-aged-idle-interface-v5-fix +++ a/drivers/block/zram/zram_drv.c @@ -309,9 +309,8 @@ static void mark_idle(struct zram *zram, zram_slot_lock(zram, index); if (zram_allocated(zram, index) && !zram_test_flag(zram, index, ZRAM_UNDER_WB)) { -#ifdef CONFIG_ZRAM_MEMORY_TRACKING + if (IS_ENABLED(CONFIG_ZRAM_MEMORY_TRACKING)) is_idle = (!cutoff || ktime_after(cutoff, zram->table[index].ac_time)); -#endif if (is_idle) zram_set_flag(zram, index, ZRAM_IDLE); }
> Also this? > > --- a/drivers/block/zram/zram_drv.c~zram-introduce-an-aged-idle-interface-v5-fix > +++ a/drivers/block/zram/zram_drv.c > @@ -309,9 +309,8 @@ static void mark_idle(struct zram *zram, > zram_slot_lock(zram, index); > if (zram_allocated(zram, index) && > !zram_test_flag(zram, index, ZRAM_UNDER_WB)) { > -#ifdef CONFIG_ZRAM_MEMORY_TRACKING > + if (IS_ENABLED(CONFIG_ZRAM_MEMORY_TRACKING)) > is_idle = (!cutoff || ktime_after(cutoff, zram->table[index].ac_time)); > -#endif > if (is_idle) > zram_set_flag(zram, index, ZRAM_IDLE); > } > _ > Hi Andrew, As written that patch won't compile when CONFIG_ZRAM_MEMORY_TRACKING=n, my guess is that the compiler pass that removes the dead branch only happens after it attempts to compile the branch itself. So it appears that even though IS_ENABLED(..) always evaluates to 0, the compile will fail because table[index].ac_time does not exist. You should get an error like this: drivers/block/zram/zram_drv.c:314:57: error: no member named 'ac_time' in 'struct zram_table_entry' (!cutoff || ktime_after(cutoff, zram->table[index].ac_time))) Brian
On (21/09/24 09:11), Brian Geffon wrote: [..] Some silly nits: > +static void mark_idle(struct zram *zram, ktime_t cutoff) > { > - struct zram *zram = dev_to_zram(dev); > + int is_idle = 1; > unsigned long nr_pages = zram->disksize >> PAGE_SHIFT; > int index; > > - if (!sysfs_streq(buf, "all")) > - return -EINVAL; > - > - down_read(&zram->init_lock); > - if (!init_done(zram)) { > - up_read(&zram->init_lock); > - return -EINVAL; > - } > - > for (index = 0; index < nr_pages; index++) { > /* > * Do not mark ZRAM_UNDER_WB slot as ZRAM_IDLE to close race. > @@ -314,14 +308,49 @@ static ssize_t idle_store(struct device *dev, > */ > zram_slot_lock(zram, index); > if (zram_allocated(zram, index) && > - !zram_test_flag(zram, index, ZRAM_UNDER_WB)) > - zram_set_flag(zram, index, ZRAM_IDLE); > + !zram_test_flag(zram, index, ZRAM_UNDER_WB)) { > +#ifdef CONFIG_ZRAM_MEMORY_TRACKING > + is_idle = (!cutoff || ktime_after(cutoff, zram->table[index].ac_time)); checkpatch "WARNING: suspect code indent for conditional statements (16, 32)" Looks like `is_idle` is at one extra indent level. > +#endif > + if (is_idle) > + zram_set_flag(zram, index, ZRAM_IDLE); > + } > zram_slot_unlock(zram, index); > } > +} > > - up_read(&zram->init_lock); > +static ssize_t idle_store(struct device *dev, > + struct device_attribute *attr, const char *buf, size_t len) > +{ > + struct zram *zram = dev_to_zram(dev); > + ktime_t cutoff_time = 0; > + ssize_t rv = -EINVAL; > > - return len; > + if (!sysfs_streq(buf, "all")) { > + /* > + * If it did not parse as 'all' try to treat it as an integer when > + * we have memory tracking enabled. > + */ > + u64 age_sec; checkpatch "WARNING: Missing a blank line after declarations" > + if (IS_ENABLED(CONFIG_ZRAM_MEMORY_TRACKING) && !kstrtoull(buf, 0, &age_sec)) > + cutoff_time = ktime_sub(ktime_get_boottime(), > + ns_to_ktime(age_sec * NSEC_PER_SEC)); > + else > + goto out; > + } > + > + down_read(&zram->init_lock); > + if (!init_done(zram)) > + goto out_unlock; > + > + /* A age_sec of 0 marks everything as idle, this is the "all" behavior */ s/age_sec/cutoff_time/ > + mark_idle(zram, cutoff_time); > + rv = len;
diff --git a/Documentation/admin-guide/blockdev/zram.rst b/Documentation/admin-guide/blockdev/zram.rst index a6fd1f9b5faf..c66efb2eeac3 100644 --- a/Documentation/admin-guide/blockdev/zram.rst +++ b/Documentation/admin-guide/blockdev/zram.rst @@ -327,6 +327,14 @@ 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 +marked as idle based on how long (in seconds) it's been since they were +last accessed:: + + echo 86400 > /sys/block/zramX/idle + +In this example all pages which haven't been accessed in more than 86400 +seconds (one day) will be marked idle. Admin can request writeback of those idle pages at right timing via:: diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index d291bedeef8e..33282f04ea32 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -291,22 +291,16 @@ static ssize_t mem_used_max_store(struct device *dev, return len; } -static ssize_t idle_store(struct device *dev, - struct device_attribute *attr, const char *buf, size_t len) +/* + * Mark all pages which are older than or equal to cutoff as IDLE. + * Callers should hold the zram init lock in read mode + */ +static void mark_idle(struct zram *zram, ktime_t cutoff) { - struct zram *zram = dev_to_zram(dev); + int is_idle = 1; unsigned long nr_pages = zram->disksize >> PAGE_SHIFT; int index; - if (!sysfs_streq(buf, "all")) - return -EINVAL; - - down_read(&zram->init_lock); - if (!init_done(zram)) { - up_read(&zram->init_lock); - return -EINVAL; - } - for (index = 0; index < nr_pages; index++) { /* * Do not mark ZRAM_UNDER_WB slot as ZRAM_IDLE to close race. @@ -314,14 +308,49 @@ static ssize_t idle_store(struct device *dev, */ zram_slot_lock(zram, index); if (zram_allocated(zram, index) && - !zram_test_flag(zram, index, ZRAM_UNDER_WB)) - zram_set_flag(zram, index, ZRAM_IDLE); + !zram_test_flag(zram, index, ZRAM_UNDER_WB)) { +#ifdef CONFIG_ZRAM_MEMORY_TRACKING + is_idle = (!cutoff || ktime_after(cutoff, zram->table[index].ac_time)); +#endif + if (is_idle) + zram_set_flag(zram, index, ZRAM_IDLE); + } zram_slot_unlock(zram, index); } +} - up_read(&zram->init_lock); +static ssize_t idle_store(struct device *dev, + struct device_attribute *attr, const char *buf, size_t len) +{ + struct zram *zram = dev_to_zram(dev); + ktime_t cutoff_time = 0; + ssize_t rv = -EINVAL; - return len; + if (!sysfs_streq(buf, "all")) { + /* + * If it did not parse as 'all' try to treat it as an integer when + * we have memory tracking enabled. + */ + u64 age_sec; + if (IS_ENABLED(CONFIG_ZRAM_MEMORY_TRACKING) && !kstrtoull(buf, 0, &age_sec)) + cutoff_time = ktime_sub(ktime_get_boottime(), + ns_to_ktime(age_sec * NSEC_PER_SEC)); + else + goto out; + } + + down_read(&zram->init_lock); + if (!init_done(zram)) + goto out_unlock; + + /* A age_sec of 0 marks everything as idle, this is the "all" behavior */ + mark_idle(zram, cutoff_time); + rv = len; + +out_unlock: + up_read(&zram->init_lock); +out: + return rv; } #ifdef CONFIG_ZRAM_WRITEBACK
This change introduces an aged idle interface to the existing idle sysfs file for zram. When CONFIG_ZRAM_MEMORY_TRACKING is enabled the idle file now also accepts an integer argument. This integer is the age (in seconds) of pages to mark as idle. The idle file still supports 'all' as it always has. This new approach allows for much more control over which pages get marked as idle. v4 -> v5: - Andrew's suggestions to use IS_ENABLED and cleanup comment. v3 -> v4: - Remove base10 restriction. v2 -> v3: - Correct unused variable warning when CONFIG_ZRAM_MEMORY_TRACKING is not enabled. v1 -> v2: - Switch to using existing idle file. - Dont compare ktime directly. Signed-off-by: Brian Geffon <bgeffon@google.com> Acked-by: Minchan Kim <minchan@kernel.org> --- Documentation/admin-guide/blockdev/zram.rst | 8 +++ drivers/block/zram/zram_drv.c | 61 +++++++++++++++------ 2 files changed, 53 insertions(+), 16 deletions(-)