This patchset introduce contextless compression API and use it on zram in order to support more compression algorithm without more overhead. The reason we need to support vairous compression algorithms is that zram's performance is highly depend on workload and compression algorithm and architecture. Every compression algorithm has it's own strong point. For example, zlib is the best for compression ratio, but, it's (de)compression speed is rather slow. Against my expectation, in my kernel build test with zram swap, in low-memory condition on x86, zlib shows best performance than others. In this case, I guess that compression ratio is the most important factor. Kernel build elapsed time in QEMU 8 CPUs 448 MB with zram swap lzo : deflate 188.3 s : 181.9 s (3% improvement) Unlike this situation, on ARM, maybe fast (de)compression speed is the most important because it's computation speed is slower than x86. Anyway, there is a concern from Sergey to use crypto API in zram. Current crypto API has a limitation that always require tfm object to (de)compress something because some of (de)compression function requires scratch buffer embedded on tfm even if some of (de)compression function doesn't require it. Due to above reason, using crypto API rather than calling compression library directly causes more memory footprint and this is why zram doesn't use crypto API before. To solve this problem, this patchset introduce contextless compression API. This new compression API doesn't require user to use tfm one by one. Tfm is only used for distinguishing compression algorithm and maybe keeping algorithm parameter so can be used concurrently. Context is now separate from tfm and user needs to allocate and manage it separately. With this separation, we can save memory in some cases and get the best performance. This patchset solves Sergey's concern perfectly and provides possibility to use various compression algorithm in zram. Thanks. Joonsoo Kim (6): crypto/compress: introduce contextless compression and remove unused pcomp crypto/lzo: support contextless compression API crypto/lz4: support contextless compressiona API crypto/deflate: support contextless compression API zram: use crypto contextless compression API to (de)compress zram: enable contextless compression alg in zram Sergey Senozhatsky (2): zram: make stream find and release functions static zram: pass zstrm down to decompression path Documentation/blockdev/zram.txt | 29 ++- crypto/Kconfig | 18 +- crypto/Makefile | 3 +- crypto/ccompress.c | 95 +++++++++ crypto/deflate.c | 96 +++++++++- crypto/lz4.c | 77 +++++++- crypto/lzo.c | 81 ++++++-- crypto/pcompress.c | 115 ----------- crypto/zlib.c | 381 ------------------------------------- drivers/block/zram/Kconfig | 13 +- drivers/block/zram/Makefile | 4 +- drivers/block/zram/zcomp.c | 104 ++++++---- drivers/block/zram/zcomp.h | 32 ++-- drivers/block/zram/zram_drv.c | 33 +++- include/crypto/compress.h | 118 ++++-------- include/crypto/internal/compress.h | 28 --- include/linux/crypto.h | 2 +- 17 files changed, 488 insertions(+), 741 deletions(-) create mode 100644 crypto/ccompress.c delete mode 100644 crypto/pcompress.c delete mode 100644 crypto/zlib.c delete mode 100644 include/crypto/internal/compress.h -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html