On Tue, Jul 07, 2015 at 08:56:59PM +0900, Sergey Senozhatsky wrote:
> `zs_compact_control' accounts the number of migrated objects but
> it has a limited lifespan -- we lose it as soon as zs_compaction()
> returns back to zram. It worked fine, because (a) zram had it's own
> counter of migrated objects and (b) only zram could trigger
> compaction. However, this does not work for automatic pool
> compaction (not issued by zram). To account objects migrated
> during auto-compaction (issued by the shrinker) we need to store
> this number in zs_pool.
>
> Define a new `struct zs_pool_stats' structure to keep zs_pool's
> stats there. It provides only `num_migrated', as of this writing,
> but it surely can be extended.
>
> A new zsmalloc zs_pool_stats() symbol exports zs_pool's stats
> back to caller.
>
> Use zs_pool_stats() in zram and remove `num_migrated' from
> zram_stats.
>
> Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
> Suggested-by: Minchan Kim <minchan@xxxxxxxxxx>
> ---
> drivers/block/zram/zram_drv.c | 11 ++++++-----
> drivers/block/zram/zram_drv.h | 1 -
> include/linux/zsmalloc.h | 6 ++++++
> mm/zsmalloc.c | 42 ++++++++++++++++++++++--------------------
> 4 files changed, 34 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
> index fb655e8..aa22fe07 100644
> --- a/drivers/block/zram/zram_drv.c
> +++ b/drivers/block/zram/zram_drv.c
> @@ -388,7 +388,6 @@ static ssize_t comp_algorithm_store(struct device *dev,
> static ssize_t compact_store(struct device *dev,
> struct device_attribute *attr, const char *buf, size_t len)
> {
> - unsigned long nr_migrated;
> struct zram *zram = dev_to_zram(dev);
> struct zram_meta *meta;
>
> @@ -399,8 +398,7 @@ static ssize_t compact_store(struct device *dev,
> }
>
> meta = zram->meta;
> - nr_migrated = zs_compact(meta->mem_pool);
> - atomic64_add(nr_migrated, &zram->stats.num_migrated);
> + zs_compact(meta->mem_pool);
> up_read(&zram->init_lock);
>
> return len;
> @@ -428,13 +426,16 @@ static ssize_t mm_stat_show(struct device *dev,
> struct device_attribute *attr, char *buf)
> {
> struct zram *zram = dev_to_zram(dev);
> + struct zs_pool_stats pool_stats = {0};
Does it work even if first member of the structure is non-scalar?
Personally I prefer memset for initliazation.
I believe modern compiler would optimize that quite well.
> u64 orig_size, mem_used = 0;
> long max_used;
> ssize_t ret;
>
> down_read(&zram->init_lock);
> - if (init_done(zram))
> + if (init_done(zram)) {
> mem_used = zs_get_total_pages(zram->meta->mem_pool);
> + zs_pool_stats(zram->meta->mem_pool, &pool_stats);
> + }
>
> orig_size = atomic64_read(&zram->stats.pages_stored);
> max_used = atomic_long_read(&zram->stats.max_used_pages);
> @@ -447,7 +448,7 @@ static ssize_t mm_stat_show(struct device *dev,
> zram->limit_pages << PAGE_SHIFT,
> max_used << PAGE_SHIFT,
> (u64)atomic64_read(&zram->stats.zero_pages),
> - (u64)atomic64_read(&zram->stats.num_migrated));
> + pool_stats.num_migrated);
> up_read(&zram->init_lock);
>
> return ret;
> diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
> index 6dbe2df..8e92339 100644
> --- a/drivers/block/zram/zram_drv.h
> +++ b/drivers/block/zram/zram_drv.h
> @@ -78,7 +78,6 @@ struct zram_stats {
> atomic64_t compr_data_size; /* compressed size of pages stored */
> atomic64_t num_reads; /* failed + successful */
> atomic64_t num_writes; /* --do-- */
> - atomic64_t num_migrated; /* no. of migrated object */
> atomic64_t failed_reads; /* can happen when memory is too low */
> atomic64_t failed_writes; /* can happen when memory is too low */
> atomic64_t invalid_io; /* non-page-aligned I/O requests */
> diff --git a/include/linux/zsmalloc.h b/include/linux/zsmalloc.h
> index 1338190..9340fce 100644
> --- a/include/linux/zsmalloc.h
> +++ b/include/linux/zsmalloc.h
> @@ -34,6 +34,11 @@ enum zs_mapmode {
> */
> };
>
> +struct zs_pool_stats {
> + /* How many objects were migrated */
> + u64 num_migrated;
> +};
> +
> struct zs_pool;
>
> struct zs_pool *zs_create_pool(char *name, gfp_t flags);
> @@ -49,4 +54,5 @@ void zs_unmap_object(struct zs_pool *pool, unsigned long handle);
> unsigned long zs_get_total_pages(struct zs_pool *pool);
> unsigned long zs_compact(struct zs_pool *pool);
>
> +void zs_pool_stats(struct zs_pool *pool, struct zs_pool_stats *stats);
> #endif
> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
> index ce1484e..db3cb2d 100644
> --- a/mm/zsmalloc.c
> +++ b/mm/zsmalloc.c
> @@ -237,16 +237,18 @@ struct link_free {
> };
>
> struct zs_pool {
> - char *name;
> + char *name;
huge tab?
>
> - struct size_class **size_class;
> - struct kmem_cache *handle_cachep;
> + struct size_class **size_class;
> + struct kmem_cache *handle_cachep;
tab?
tab?
>
> - gfp_t flags; /* allocation flags used when growing pool */
> - atomic_long_t pages_allocated;
Why changes comment position?
> + /* Allocation flags used when growing pool */
> + gfp_t flags;
> + atomic_long_t pages_allocated;
>
Why blank line?
> + struct zs_pool_stats stats;
> #ifdef CONFIG_ZSMALLOC_STAT
> - struct dentry *stat_dentry;
> + struct dentry *stat_dentry;
Tab.
> #endif
> };
>
> @@ -1587,7 +1589,7 @@ struct zs_compact_control {
> /* Starting object index within @s_page which used for live object
> * in the subpage. */
> int index;
> - /* how many of objects are migrated */
> + /* How many of objects were migrated */
> int nr_migrated;
> };
>
> @@ -1599,7 +1601,6 @@ static int migrate_zspage(struct zs_pool *pool, struct size_class *class,
> struct page *s_page = cc->s_page;
> struct page *d_page = cc->d_page;
> unsigned long index = cc->index;
> - int nr_migrated = 0;
> int ret = 0;
>
> while (1) {
> @@ -1626,13 +1627,12 @@ static int migrate_zspage(struct zs_pool *pool, struct size_class *class,
> record_obj(handle, free_obj);
> unpin_tag(handle);
> obj_free(pool, class, used_obj);
> - nr_migrated++;
> + cc->nr_migrated++;
> }
>
> /* Remember last position in this iteration */
> cc->s_page = s_page;
> cc->index = index;
> - cc->nr_migrated = nr_migrated;
>
> return ret;
> }
> @@ -1707,14 +1707,13 @@ static unsigned long zs_can_compact(struct size_class *class)
> return obj_wasted * get_pages_per_zspage(class->size);
> }
>
> -static unsigned long __zs_compact(struct zs_pool *pool,
> - struct size_class *class)
> +static void __zs_compact(struct zs_pool *pool, struct size_class *class)
> {
> struct zs_compact_control cc;
> struct page *src_page;
> struct page *dst_page = NULL;
> - unsigned long nr_total_migrated = 0;
>
> + cc.nr_migrated = 0;
> spin_lock(&class->lock);
> while ((src_page = isolate_source_page(class))) {
>
> @@ -1736,7 +1735,6 @@ static unsigned long __zs_compact(struct zs_pool *pool,
> break;
>
> putback_zspage(pool, class, dst_page);
> - nr_total_migrated += cc.nr_migrated;
> }
>
> /* Stop if we couldn't find slot */
> @@ -1746,7 +1744,6 @@ static unsigned long __zs_compact(struct zs_pool *pool,
> putback_zspage(pool, class, dst_page);
> putback_zspage(pool, class, src_page);
> spin_unlock(&class->lock);
> - nr_total_migrated += cc.nr_migrated;
> cond_resched();
> spin_lock(&class->lock);
> }
> @@ -1754,15 +1751,14 @@ static unsigned long __zs_compact(struct zs_pool *pool,
> if (src_page)
> putback_zspage(pool, class, src_page);
>
> - spin_unlock(&class->lock);
> + pool->stats.num_migrated += cc.nr_migrated;
>
> - return nr_total_migrated;
> + spin_unlock(&class->lock);
> }
>
> unsigned long zs_compact(struct zs_pool *pool)
> {
> int i;
> - unsigned long nr_migrated = 0;
> struct size_class *class;
>
> for (i = zs_size_classes - 1; i >= 0; i--) {
> @@ -1771,13 +1767,19 @@ unsigned long zs_compact(struct zs_pool *pool)
> continue;
> if (class->index != i)
> continue;
> - nr_migrated += __zs_compact(pool, class);
> + __zs_compact(pool, class);
> }
>
> - return nr_migrated;
> + return pool->stats.num_migrated;
> }
> EXPORT_SYMBOL_GPL(zs_compact);
>
> +void zs_pool_stats(struct zs_pool *pool, struct zs_pool_stats *stats)
> +{
> + memcpy(stats, &pool->stats, sizeof(struct zs_pool_stats));
> +}
> +EXPORT_SYMBOL_GPL(zs_pool_stats);
> +
> /**
> * zs_create_pool - Creates an allocation pool to work from.
> * @flags: allocation flags used to allocate pool metadata
> --
> 2.4.5
>
--
Kind regards,
Minchan Kim
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