From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 91443613D for ; Wed, 24 Jul 2024 19:27:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721849236; cv=none; b=sWr8B6B8HmlZXvpAqS7BN5wIkfW+ydXnjD6TpMgoIdjz/L1RYAabBikh155422gwCfdK1ThqxRitrD4LEvKLnfT/dYowZzZ0jV+87J0qe5a+STJRQs4EFhWBcmmUk4qJJzkkz5f5T4fmTVDySGEhTx8mBLKcf3gyeddUMEEEA/8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721849236; c=relaxed/simple; bh=vcsMyaL/J5TC6qyjVr29cWtArdPtJr3aeW1ZE4q5y6o=; h=Date:To:From:Subject:Message-Id; b=tlIJIrVpR2bkStn3PVxFOF/KsBWY5bmVWd/n3DQSWpWMg6HFhuirOyPgNuME0QMmK4XhpX91+YlNRrOTpY+cWrX0Sg/mxVI6gjLwj3suQcbwlhWDgP5TC5GmmdcUh19pAY+yylDdX5A5V2EW+vbadUQx9X0+Jw6JuulsScFt2pc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=FrcRLtrU; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="FrcRLtrU" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 657C5C32781; Wed, 24 Jul 2024 19:27:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1721849236; bh=vcsMyaL/J5TC6qyjVr29cWtArdPtJr3aeW1ZE4q5y6o=; h=Date:To:From:Subject:From; b=FrcRLtrUX7x0dYgiUaFLCi7ZYGEg1gY8SpavkKzp8J1rROJ3s3DbE5JPI2/FbgNPc KRYag+mmZ1FVeLg0V3tfli9FlNAmUIqtek/fUmso/RqtD9HtD4o8oGH1aA6CTXE2EX Xz/YTT4AfmtX8tGx4NIjtzOFeEf5fTyfgV82Vlv8= Date: Wed, 24 Jul 2024 12:27:15 -0700 To: mm-commits@vger.kernel.org,terrelln@fb.com,nphamcs@gmail.com,ngupta@vflare.org,minchan@kernel.org,senozhatsky@chromium.org,akpm@linux-foundation.org From: Andrew Morton Subject: + documentation-zram-add-documentation-for-algorithm-parameters.patch added to mm-unstable branch Message-Id: <20240724192716.657C5C32781@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: Documentation/zram: add documentation for algorithm parameters has been added to the -mm mm-unstable branch. Its filename is documentation-zram-add-documentation-for-algorithm-parameters.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/documentation-zram-add-documentation-for-algorithm-parameters.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Sergey Senozhatsky Subject: Documentation/zram: add documentation for algorithm parameters Date: Fri, 12 Jul 2024 14:18:34 +0900 Document brief description of compression algorithms' parameters: compression level and pre-trained dictionary. Link: https://lkml.kernel.org/r/20240712051850.484318-24-senozhatsky@chromium.org Signed-off-by: Sergey Senozhatsky Cc: Minchan Kim Cc: Nhat Pham Cc: Nick Terrell Cc: Nitin Gupta Signed-off-by: Andrew Morton --- Documentation/admin-guide/blockdev/zram.rst | 45 ++++++++++++++---- 1 file changed, 36 insertions(+), 9 deletions(-) --- a/Documentation/admin-guide/blockdev/zram.rst~documentation-zram-add-documentation-for-algorithm-parameters +++ a/Documentation/admin-guide/blockdev/zram.rst @@ -102,15 +102,33 @@ Examples:: #select lzo compression algorithm echo lzo > /sys/block/zram0/comp_algorithm -For the time being, the `comp_algorithm` content does not necessarily -show every compression algorithm supported by the kernel. We keep this -list primarily to simplify device configuration and one can configure -a new device with a compression algorithm that is not listed in -`comp_algorithm`. The thing is that, internally, ZRAM uses Crypto API -and, if some of the algorithms were built as modules, it's impossible -to list all of them using, for instance, /proc/crypto or any other -method. This, however, has an advantage of permitting the usage of -custom crypto compression modules (implementing S/W or H/W compression). +For the time being, the `comp_algorithm` content shows only compression +algorithms that are supported by zram. + +It is also possible to pass algorithm specific configuration parameters:: + + #set compression level to 8 + echo "zstd level=8" > /sys/block/zram0/comp_algorithm + +Note that `comp_algorithm` also supports `algo=name` format:: + + #set compression level to 8 + echo "algo=zstd level=8" > /sys/block/zram0/comp_algorithm + +Certain compression algorithms support pre-trained dictionaries, which +significantly change algorithms' characteristics. In order to configure +compression algorithm to use external pre-trained dictionary, pass full +path to the dictionary along with other parameters:: + + #pass path to pre-trained dictionary + echo "algo=zstd dict=/etc/dictioary" > /sys/block/zram0/comp_algorithm + +Parameters are algorithm specific: not all algorithms support pre-trained +dictionaries, not all algorithms support 'level'. Furthermore, for certain +algorithms 'level' controls the compression level (the higher the value the +better the compression ratio, it even can take negatives values for some +algorithms), for other algorithms 'level' is acceleration level (the higher +the value the lower the compression ratio). 4) Set Disksize =============== @@ -442,6 +460,15 @@ configuration::: #select deflate recompression algorithm, priority 2 echo "algo=deflate priority=2" > /sys/block/zramX/recomp_algorithm +The `recomp_algorithm` also supports algorithm configuration parameters, e.g. +compression level and pre-trained dircionary:: + + #pass compression level + echo "algo=zstd level=8" > /sys/block/zramX/recomp_algorithm + + #pass path to pre-trained dictionary + echo "algo=zstd dict=/etc/dictioary" > /sys/block/zramX/recomp_algorithm + Another device attribute that CONFIG_ZRAM_MULTI_COMP enables is recompress, which controls recompression. _ Patches currently in -mm which might be from senozhatsky@chromium.org are lib-zstd-export-api-needed-for-dictionary-support.patch lib-lz4hc-export-lz4_resetstreamhc-symbol.patch lib-zstd-fix-null-deref-in-zstd_createcdict_advanced2.patch zram-introduce-custom-comp-backends-api.patch zram-add-lzo-and-lzorle-compression-backends-support.patch zram-add-lz4-compression-backend-support.patch zram-add-lz4hc-compression-backend-support.patch zram-add-zstd-compression-backend-support.patch zram-pass-estimated-src-size-hint-to-zstd.patch zram-add-zlib-compression-backend-support.patch zram-add-842-compression-backend-support.patch zram-check-that-backends-array-has-at-least-one-backend.patch zram-introduce-zcomp_params-structure.patch zram-recalculate-zstd-compression-params-once.patch zram-extend-comp_algorithm-attr-write-handling.patch zram-add-support-for-dict-comp-config.patch zram-introduce-zcomp_req-structure.patch zram-introduce-zcomp_ctx-structure.patch zram-move-immutable-comp-params-away-from-per-cpu-context.patch zram-add-dictionary-support-to-lz4.patch zram-add-dictionary-support-to-lz4hc.patch zram-add-dictionary-support-to-zstd-backend.patch documentation-zram-add-documentation-for-algorithm-parameters.patch