On Wed, Nov 09, 2022 at 08:50:34PM +0900, Sergey Senozhatsky wrote: > Hello, > > This series adds support for multiple compression streams. > The main idea is that different compression algorithms have different > characteristics and zram may benefit when it uses a combination of > algorithms: a default algorithm that is faster but have lower > compression rate and a secondary algorithm that can use higher > compression rate at a price of slower compression/decompression. > > There are several use-case for this functionality: > > - huge pages re-compression: zstd or deflate can successfully > compress huge pages (~50% of huge pages on my synthetic ChromeOS > tests), IOW pages that lzo was not able to compress. > > - idle pages re-compression: idle/cold pages sit in the memory > and we may reduce zsmalloc memory usage if we recompress those > idle pages. > > User-space has a number of ways to control the behavior > and impact of zram recompression: what type of pages should be > recompressed, size watermarks, etc. Please refer to documentation > patch. > > v5: > -- Addressed (very valuable) review feedback from Minchan > -- Extended documentation > -- We now do chain recompression, tryin algos in order of their priority > -- Support up to 4 compression streams > -- Added named parameters to recomp_algorithm and recompress sysfs knobs > -- Cherry-picked patch from Alexey > -- Store algo priority in mete flags > -- Renamed some fo the flags > -- Added incompressible bit to block state output > -- Added incompressible writeback > -- etc. > > v4: > -- added IS_ERR_VALUE patch (Andrew) > -- documented SIZE units (bytes) (Andrew) > -- re-phrased writeback BIO error comment (Andrew) > -- return zs_malloc() error code from zram_recompress() > -- do not lose zram_recompress() error in recompress_store() > -- corrected a typo > -- fixed previous rebase errors > -- rebased the series > > v3: > -- conditionally reschedule during recompression loop so that > we don't stall RCU grace periods > -- fixed a false-positive WARN_ON > > v2: > -- rebased > -- mark completely incompressible pages (neither default nor secondary > algorithm can compress them) with a new flag so that we don't attempt > to recompress them all the time > > Alexey Romanov (1): > zram: add size class equals check into recompression > > Sergey Senozhatsky (12): > zram: Preparation for multi-zcomp support > zram: Add recompression algorithm sysfs knob > zram: Factor out WB and non-WB zram read functions > zram: Introduce recompress sysfs knob > zram: Add recompress flag to read_block_state() > zram: Clarify writeback_store() comment > zram: Use IS_ERR_VALUE() to check for zs_malloc() errors > zram: remove redundant checks from zram_recompress() > zram: Add algo parameter support to zram_recompress() > documentation: Add zram recompression documentation > zram: add incompressible writeback > zram: Add incompressible flag to read_block_state() > > Documentation/admin-guide/blockdev/zram.rst | 100 +++- > drivers/block/zram/Kconfig | 9 + > drivers/block/zram/zcomp.c | 6 +- > drivers/block/zram/zcomp.h | 2 +- > drivers/block/zram/zram_drv.c | 604 +++++++++++++++++--- > drivers/block/zram/zram_drv.h | 22 +- > include/linux/zsmalloc.h | 2 + > mm/zsmalloc.c | 21 + > 8 files changed, 685 insertions(+), 81 deletions(-) Acked-by: Minchan Kim <minchan@xxxxxxxxxx> Thanks!
