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Date: Fri, 25 Sep 2015 14:31:09 +0900 From: Joonsoo Kim <iamjoonsoo.kim@....com> To: Minchan Kim <minchan@...nel.org> Cc: Andrew Morton <akpm@...ux-foundation.org>, Nitin Gupta <ngupta@...are.org>, Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>, linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org, Herbert Xu <herbert@...dor.apana.org.au>, "David S. Miller" <davem@...emloft.net>, Stephan Mueller <smueller@...onox.de> Subject: Re: [PATCH v3 0/9] zram: introduce crypto decompress noctx API and use it on zram On Mon, Sep 21, 2015 at 12:58:12PM +0900, Minchan Kim wrote: > On Fri, Sep 18, 2015 at 02:19:15PM +0900, Joonsoo Kim wrote: > > This patchset makes zram to use crypto API in order to support > > more compression algorithm. > > > > 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. Unlike this situation, on ARM, maybe fast > > (de)compression speed is the most important because it's computation speed > > is slower than x86. > > Fair enough. lzo and lz4 cannot cover all of workloads so surely, there are > workloads other compressor algorithm can win. As well, we could support > H/W compressor with crypto support so I think crypto is a way to go. Hello, Minchan. Good! > > One thing I have a concern is I don't want to bind some of compressor > algorithm to zram statically. User can see what kinds of crypto compressor > support in his system via /proc/crypto and use it dynamically. > I hope zram supports it. Okay. I will handle it next version. > > > > 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 > > Nice catch from Sergey! > > > compression library directly causes more memory footprint and this is > > why zram doesn't use crypto API before. > > > > In this patchset, crypto compress noctx API is introduced to reduce memory > > footprint caused by maintaining multiple tfm and zram uses it. Before > > noctx API, zram's performace is down-graded if tfm is insufficient. But, > > after applying noctx API, performace is restored. > > > > This addresses Sergey's concern perfectly and provides possibility to use > > various compression algorithm in zram. > > > > Following is zram's read performance number. > > > > * iozone -t 4 -R -r 16K -s 60M -I +Z -i 0 -i 1 > > * max_stream is set to 1 > > * Output is in Kbytes/sec > > > > zram-base vs zram-crypto vs zram-crypto-noctx > > > > Read 10411701.88 6426911.62 9423894.38 > > Re-read 10017386.62 6428218.88 11000063.50 > > Another patch and number we need to merge this patchset is zlib support > patchset and number you had experiement. Okay. Will include. Thanks. > > > > Thanks. > > > > Joonsoo Kim (7): > > crypto: introduce decompression API that can be called via sharable > > tfm object > > crypto/lzo: support decompress_noctx > > crypyo/lz4: support decompress_noctx > > crypto/lz4hc: support decompress_noctx > > crypto/842: support decompress_noctx > > zram: use crypto API for compression > > zram: use crypto decompress_noctx API > > > > Sergey Senozhatsky (2): > > zram: make stream find and release functions static > > zram: pass zstrm down to decompression path > > > > crypto/842.c | 9 +++- > > crypto/compress.c | 36 +++++++++++++++ > > crypto/crypto_null.c | 3 +- > > crypto/deflate.c | 3 +- > > crypto/lz4.c | 9 +++- > > crypto/lz4hc.c | 9 +++- > > crypto/lzo.c | 9 +++- > > drivers/block/zram/Kconfig | 8 ++-- > > drivers/block/zram/Makefile | 4 +- > > drivers/block/zram/zcomp.c | 102 +++++++++++++++++++++++++++++++---------- > > drivers/block/zram/zcomp.h | 42 +++++++---------- > > drivers/block/zram/zcomp_lz4.c | 47 ------------------- > > drivers/block/zram/zcomp_lz4.h | 17 ------- > > drivers/block/zram/zcomp_lzo.c | 47 ------------------- > > drivers/block/zram/zcomp_lzo.h | 17 ------- > > drivers/block/zram/zram_drv.c | 32 +++++++++---- > > include/linux/crypto.h | 20 ++++++++ > > 17 files changed, 211 insertions(+), 203 deletions(-) > > delete mode 100644 drivers/block/zram/zcomp_lz4.c > > delete mode 100644 drivers/block/zram/zcomp_lz4.h > > delete mode 100644 drivers/block/zram/zcomp_lzo.c > > delete mode 100644 drivers/block/zram/zcomp_lzo.h > > > > -- > > 1.9.1 > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@...r.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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