| Message ID | 20240329094050.2815699-1-senozhatsky@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [PATCHv2] zram: add max_pages param to recompression | expand |
On Fri, Mar 29, 2024 at 5:40 AM Sergey Senozhatsky <senozhatsky@chromium.org> wrote: > > Introduce "max_pages" param to recompress device attribute > which sets an upper limit on the number of entries (pages) > zram attempts to recompress (in this particular recompression > call). S/W recompression can be quite expensive so limiting > the number of pages recompress touches can be quite helpful. > > Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org> Acked-by: Brian Geffon <bgeffon@google.com> > > --- > Documentation/admin-guide/blockdev/zram.rst | 5 ++++ > drivers/block/zram/zram_drv.c | 31 +++++++++++++++++++-- > 2 files changed, 33 insertions(+), 3 deletions(-) > > diff --git a/Documentation/admin-guide/blockdev/zram.rst b/Documentation/admin-guide/blockdev/zram.rst > index ee2b0030d416..091e8bb38887 100644 > --- a/Documentation/admin-guide/blockdev/zram.rst > +++ b/Documentation/admin-guide/blockdev/zram.rst > @@ -466,6 +466,11 @@ of equal or greater size::: > #recompress idle pages larger than 2000 bytes > echo "type=idle threshold=2000" > /sys/block/zramX/recompress > > +It is also possible to limit the number of pages zram re-compression will > +attempt to recompress::: > + > + echo "type=huge_idle max_pages=42" > /sys/block/zramX/recompress > + > Recompression of idle pages requires memory tracking. > > During re-compression for every page, that matches re-compression criteria, > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c > index f0639df6cd18..4cf38f7d3e0a 100644 > --- a/drivers/block/zram/zram_drv.c > +++ b/drivers/block/zram/zram_drv.c > @@ -1568,7 +1568,8 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, > * Corresponding ZRAM slot should be locked. > */ > static int zram_recompress(struct zram *zram, u32 index, struct page *page, > - u32 threshold, u32 prio, u32 prio_max) > + u64 *num_recomp_pages, u32 threshold, u32 prio, > + u32 prio_max) > { > struct zcomp_strm *zstrm = NULL; > unsigned long handle_old; > @@ -1645,6 +1646,15 @@ static int zram_recompress(struct zram *zram, u32 index, struct page *page, > if (!zstrm) > return 0; > > + /* > + * Decrement the limit (if set) on pages we can recompress, even > + * when current recompression was unsuccessful or did not compress > + * the page below the threshold, because we still spent resources > + * on it. > + */ > + if (*num_recomp_pages) > + *num_recomp_pages -= 1; > + > if (class_index_new >= class_index_old) { > /* > * Secondary algorithms failed to re-compress the page > @@ -1710,6 +1720,7 @@ static ssize_t recompress_store(struct device *dev, > struct zram *zram = dev_to_zram(dev); > unsigned long nr_pages = zram->disksize >> PAGE_SHIFT; > char *args, *param, *val, *algo = NULL; > + u64 num_recomp_pages = ULLONG_MAX; > u32 mode = 0, threshold = 0; > unsigned long index; > struct page *page; > @@ -1732,6 +1743,17 @@ static ssize_t recompress_store(struct device *dev, > continue; > } > > + if (!strcmp(param, "max_pages")) { > + /* > + * Limit the number of entries (pages) we attempt to > + * recompress. > + */ > + ret = kstrtoull(val, 10, &num_recomp_pages); > + if (ret) > + return ret; > + continue; > + } > + > if (!strcmp(param, "threshold")) { > /* > * We will re-compress only idle objects equal or > @@ -1788,6 +1810,9 @@ static ssize_t recompress_store(struct device *dev, > for (index = 0; index < nr_pages; index++) { > int err = 0; > > + if (!num_recomp_pages) > + break; > + > zram_slot_lock(zram, index); > > if (!zram_allocated(zram, index)) > @@ -1807,8 +1832,8 @@ static ssize_t recompress_store(struct device *dev, > zram_test_flag(zram, index, ZRAM_INCOMPRESSIBLE)) > goto next; > > - err = zram_recompress(zram, index, page, threshold, > - prio, prio_max); > + err = zram_recompress(zram, index, page, &num_recomp_pages, > + threshold, prio, prio_max); > next: > zram_slot_unlock(zram, index); > if (err) { > -- > 2.44.0.478.gd926399ef9-goog >
diff --git a/Documentation/admin-guide/blockdev/zram.rst b/Documentation/admin-guide/blockdev/zram.rst index ee2b0030d416..091e8bb38887 100644 --- a/Documentation/admin-guide/blockdev/zram.rst +++ b/Documentation/admin-guide/blockdev/zram.rst @@ -466,6 +466,11 @@ of equal or greater size::: #recompress idle pages larger than 2000 bytes echo "type=idle threshold=2000" > /sys/block/zramX/recompress +It is also possible to limit the number of pages zram re-compression will +attempt to recompress::: + + echo "type=huge_idle max_pages=42" > /sys/block/zramX/recompress + Recompression of idle pages requires memory tracking. During re-compression for every page, that matches re-compression criteria, diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index f0639df6cd18..4cf38f7d3e0a 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -1568,7 +1568,8 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, * Corresponding ZRAM slot should be locked. */ static int zram_recompress(struct zram *zram, u32 index, struct page *page, - u32 threshold, u32 prio, u32 prio_max) + u64 *num_recomp_pages, u32 threshold, u32 prio, + u32 prio_max) { struct zcomp_strm *zstrm = NULL; unsigned long handle_old; @@ -1645,6 +1646,15 @@ static int zram_recompress(struct zram *zram, u32 index, struct page *page, if (!zstrm) return 0; + /* + * Decrement the limit (if set) on pages we can recompress, even + * when current recompression was unsuccessful or did not compress + * the page below the threshold, because we still spent resources + * on it. + */ + if (*num_recomp_pages) + *num_recomp_pages -= 1; + if (class_index_new >= class_index_old) { /* * Secondary algorithms failed to re-compress the page @@ -1710,6 +1720,7 @@ static ssize_t recompress_store(struct device *dev, struct zram *zram = dev_to_zram(dev); unsigned long nr_pages = zram->disksize >> PAGE_SHIFT; char *args, *param, *val, *algo = NULL; + u64 num_recomp_pages = ULLONG_MAX; u32 mode = 0, threshold = 0; unsigned long index; struct page *page; @@ -1732,6 +1743,17 @@ static ssize_t recompress_store(struct device *dev, continue; } + if (!strcmp(param, "max_pages")) { + /* + * Limit the number of entries (pages) we attempt to + * recompress. + */ + ret = kstrtoull(val, 10, &num_recomp_pages); + if (ret) + return ret; + continue; + } + if (!strcmp(param, "threshold")) { /* * We will re-compress only idle objects equal or @@ -1788,6 +1810,9 @@ static ssize_t recompress_store(struct device *dev, for (index = 0; index < nr_pages; index++) { int err = 0; + if (!num_recomp_pages) + break; + zram_slot_lock(zram, index); if (!zram_allocated(zram, index)) @@ -1807,8 +1832,8 @@ static ssize_t recompress_store(struct device *dev, zram_test_flag(zram, index, ZRAM_INCOMPRESSIBLE)) goto next; - err = zram_recompress(zram, index, page, threshold, - prio, prio_max); + err = zram_recompress(zram, index, page, &num_recomp_pages, + threshold, prio, prio_max); next: zram_slot_unlock(zram, index); if (err) {
Introduce "max_pages" param to recompress device attribute which sets an upper limit on the number of entries (pages) zram attempts to recompress (in this particular recompression call). S/W recompression can be quite expensive so limiting the number of pages recompress touches can be quite helpful. Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org> --- Documentation/admin-guide/blockdev/zram.rst | 5 ++++ drivers/block/zram/zram_drv.c | 31 +++++++++++++++++++-- 2 files changed, 33 insertions(+), 3 deletions(-)