| Message ID | 1626763658-27748-1-git-send-email-huangzhaoyang@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | driver: zram: fix wrong counting on pages_store | expand |
On (21/07/20 14:47), Huangzhaoyang wrote: > It makes the statistic confused when counting pages_store in during writeback. > pages_store should just reflect the swapped pages on ZRAM, while bd_writes be > responsible for writeback things. > > Signed-off-by: Zhaoyang Huang <zhaoyang.huang@unisoc.com> > --- > drivers/block/zram/zram_drv.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c > index cf8deec..6bdaa9d 100644 > --- a/drivers/block/zram/zram_drv.c > +++ b/drivers/block/zram/zram_drv.c > @@ -765,7 +765,6 @@ static ssize_t writeback_store(struct device *dev, > zram_set_flag(zram, index, ZRAM_WB); > zram_set_element(zram, index, blk_idx); > blk_idx = 0; > - atomic64_inc(&zram->stats.pages_stored); Yeah, I think we don't need it here. Minchan, what do you think?
On Mon, Jul 26, 2021 at 10:27:40AM +0900, Sergey Senozhatsky wrote: > On (21/07/20 14:47), Huangzhaoyang wrote: > > It makes the statistic confused when counting pages_store in during writeback. > > pages_store should just reflect the swapped pages on ZRAM, while bd_writes be > > responsible for writeback things. > > > > Signed-off-by: Zhaoyang Huang <zhaoyang.huang@unisoc.com> > > --- > > drivers/block/zram/zram_drv.c | 1 - > > 1 file changed, 1 deletion(-) > > > > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c > > index cf8deec..6bdaa9d 100644 > > --- a/drivers/block/zram/zram_drv.c > > +++ b/drivers/block/zram/zram_drv.c > > @@ -765,7 +765,6 @@ static ssize_t writeback_store(struct device *dev, > > zram_set_flag(zram, index, ZRAM_WB); > > zram_set_element(zram, index, blk_idx); > > blk_idx = 0; > > - atomic64_inc(&zram->stats.pages_stored); > > Yeah, I think we don't need it here. > > Minchan, what do you think? What pages_stored currently represents is orig_data_size from mm_stat ================ ============================================================= orig_data_size uncompressed size of data stored in this disk. Unit: bytes Thus, if we don't increase it after zram_free_page, it loses what's the original data size which would be important to calculate compression ratio along with compr_data_size.
On Tue, Jul 27, 2021 at 1:53 AM Minchan Kim <minchan@kernel.org> wrote: > > On Mon, Jul 26, 2021 at 10:27:40AM +0900, Sergey Senozhatsky wrote: > > On (21/07/20 14:47), Huangzhaoyang wrote: > > > It makes the statistic confused when counting pages_store in during writeback. > > > pages_store should just reflect the swapped pages on ZRAM, while bd_writes be > > > responsible for writeback things. > > > > > > Signed-off-by: Zhaoyang Huang <zhaoyang.huang@unisoc.com> > > > --- > > > drivers/block/zram/zram_drv.c | 1 - > > > 1 file changed, 1 deletion(-) > > > > > > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c > > > index cf8deec..6bdaa9d 100644 > > > --- a/drivers/block/zram/zram_drv.c > > > +++ b/drivers/block/zram/zram_drv.c > > > @@ -765,7 +765,6 @@ static ssize_t writeback_store(struct device *dev, > > > zram_set_flag(zram, index, ZRAM_WB); > > > zram_set_element(zram, index, blk_idx); > > > blk_idx = 0; > > > - atomic64_inc(&zram->stats.pages_stored); > > > > Yeah, I think we don't need it here. > > > > Minchan, what do you think? > > What pages_stored currently represents is orig_data_size from mm_stat > > ================ ============================================================= > orig_data_size uncompressed size of data stored in this disk. > Unit: bytes > > Thus, if we don't increase it after zram_free_page, it loses what's > the original data size which would be important to calculate > compression ratio along with compr_data_size. zram_free_page?? What the commit try to fix is pages_stored being increased incorrectly in writeback_store, which will lead to wrong statistic on orig size of ZRAM.
On Tue, Jul 27, 2021 at 9:32 AM Zhaoyang Huang <huangzhaoyang@gmail.com> wrote: > > On Tue, Jul 27, 2021 at 1:53 AM Minchan Kim <minchan@kernel.org> wrote: > > > > On Mon, Jul 26, 2021 at 10:27:40AM +0900, Sergey Senozhatsky wrote: > > > On (21/07/20 14:47), Huangzhaoyang wrote: > > > > It makes the statistic confused when counting pages_store in during writeback. > > > > pages_store should just reflect the swapped pages on ZRAM, while bd_writes be > > > > responsible for writeback things. > > > > > > > > Signed-off-by: Zhaoyang Huang <zhaoyang.huang@unisoc.com> > > > > --- > > > > drivers/block/zram/zram_drv.c | 1 - > > > > 1 file changed, 1 deletion(-) > > > > > > > > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c > > > > index cf8deec..6bdaa9d 100644 > > > > --- a/drivers/block/zram/zram_drv.c > > > > +++ b/drivers/block/zram/zram_drv.c > > > > @@ -765,7 +765,6 @@ static ssize_t writeback_store(struct device *dev, > > > > zram_set_flag(zram, index, ZRAM_WB); > > > > zram_set_element(zram, index, blk_idx); > > > > blk_idx = 0; > > > > - atomic64_inc(&zram->stats.pages_stored); > > > > > > Yeah, I think we don't need it here. > > > > > > Minchan, what do you think? > > > > What pages_stored currently represents is orig_data_size from mm_stat > > > > ================ ============================================================= > > orig_data_size uncompressed size of data stored in this disk. > > Unit: bytes > > > > Thus, if we don't increase it after zram_free_page, it loses what's > > the original data size which would be important to calculate > > compression ratio along with compr_data_size. > zram_free_page?? What the commit try to fix is pages_stored being > increased incorrectly in writeback_store, which will lead to wrong > statistic on orig size of ZRAM. OK, if I understand right, I think what you mean is the page count corresponding to SWAP should be still available even if it is written back to the backing dev.So we need to increase page_stored again after zram_free_page free it.
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index cf8deec..6bdaa9d 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -765,7 +765,6 @@ static ssize_t writeback_store(struct device *dev, zram_set_flag(zram, index, ZRAM_WB); zram_set_element(zram, index, blk_idx); blk_idx = 0; - atomic64_inc(&zram->stats.pages_stored); spin_lock(&zram->wb_limit_lock); if (zram->wb_limit_enable && zram->bd_wb_limit > 0) zram->bd_wb_limit -= 1UL << (PAGE_SHIFT - 12);