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 B0B142FE07D for ; Fri, 13 Mar 2026 03:06:46 +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=1773371206; cv=none; b=Br9gnsx/ZDHm0aTVBBkcEQXKjWuYtse6nSH7QldXkiqXFObhp1cEv5J5KxlrMHm2XeXFLs0nkYhDdTAsuimx3p/lYxZ1Ugdje3VFyJfWS2Obfo+W6XbOEI4GBM5ZEw9XScHOWWZhjmY/NtGR2czidKgTsAFpfo10Gb2JIhDTx2I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773371206; c=relaxed/simple; bh=vDoHGHMK31jZzXq900nOQkqHlFXBrmfNEMLGnoG669U=; h=Date:To:From:Subject:Message-Id; b=T+RduyM7QDmR7OiLZu6BFbRC8DRTSGZRcVGnzOV/mhF4FDgcE6TsDi71iwxur8t6Qa1vCfIUSj5+WnJz7DVzmnDfbpFPG+KTIcMtIBMfzoZVxPq4TQepsrkT87drZEUgmGplUkkgDXWsagUAzQKmALPwJoaYIHJSB0mHR2ePK58= 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=syc0Xlx1; 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="syc0Xlx1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3795EC4CEF7; Fri, 13 Mar 2026 03:06:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1773371206; bh=vDoHGHMK31jZzXq900nOQkqHlFXBrmfNEMLGnoG669U=; h=Date:To:From:Subject:From; b=syc0Xlx1dCxCf9OgjLoVEjBpS/ZnRhzwwQQ/0nQI5EPJ2gs7VTWV3jIskql3dssdJ CSZM4FpeWBYYq8vsIsc+M0sokbCDN1tMXmcPbLxKl83muftg92OOHxDrv34UIW+O5D XUfPEP9TiwjF8G92W7myh3/a3zFqNc1hdYms6wVw= Date: Thu, 12 Mar 2026 20:06:45 -0700 To: mm-commits@vger.kernel.org,surenb@google.com,senozhatsky@chromium.org,minchan@kernel.org,axboe@kernel.dk,gaoxu2@honor.com,akpm@linux-foundation.org From: Andrew Morton Subject: + zram-optimize-lz4-dictionary-compression-performance-v2.patch added to mm-new branch Message-Id: <20260313030646.3795EC4CEF7@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: zram: optimize LZ4 dictionary compression performance has been added to the -mm mm-new branch. Its filename is zram-optimize-lz4-dictionary-compression-performance-v2.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/zram-optimize-lz4-dictionary-compression-performance-v2.patch This patch will later appear in the mm-new branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Note, mm-new is a provisional staging ground for work-in-progress patches, and acceptance into mm-new is a notification for others take notice and to finish up reviews. Please do not hesitate to respond to review feedback and post updated versions to replace or incrementally fixup patches in mm-new. The mm-new branch of mm.git is not included in linux-next If a few days of testing in mm-new is successful, the patch will me moved into mm.git's mm-unstable branch, which is included in linux-next 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 various branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there most days ------------------------------------------------------ From: gao xu Subject: zram: optimize LZ4 dictionary compression performance Date: Fri, 13 Mar 2026 02:41:14 +0000 Calling `LZ4_loadDict()` repeatedly in Zram causes significant overhead due to its internal dictionary pre-processing. This commit introduces a template stream mechanism to pre-process the dictionary only once when the dictionary is initially set or modified. It then efficiently copies this state for subsequent compressions. Verification Test Items: Test Platform: android16-6.12 1. Collect Anonymous Page Dataset 1) Apply the following patch: static bool zram_meta_alloc(struct zram *zram, u64 disksize) if (!huge_class_size) - huge_class_size = zs_huge_class_size(zram->mem_pool); + huge_class_size = 0; 2）Install multiple apps and monkey testing until SwapFree is close to 0. 3）Execute the following command to export data: dd if=/dev/block/zram0 of=/data/samples/zram_dump.img bs=4K 2. Train Dictionary Since LZ4 does not have a dedicated dictionary training tool, the zstd tool can be used for training[1]. The command is as follows: zstd --train /data/samples/* --split=4096 --maxdict=64KB -o /vendor/etc/dict_data 3. Test Code adb shell "dd if=/data/samples/zram_dump.img of=/dev/test_pattern bs=4096 count=131072 conv=fsync" adb shell "swapoff /dev/block/zram0" adb shell "echo 1 > /sys/block/zram0/reset" adb shell "echo lz4 > /sys/block/zram0/comp_algorithm" adb shell "echo dict=/vendor/etc/dict_data > /sys/block/zram0/algorithm_params" adb shell "echo 6G > /sys/block/zram0/disksize" echo "Start Compression" adb shell "taskset 80 dd if=/dev/test_pattern of=/dev/block/zram0 bs=4096 count=131072 conv=fsync" echo. echo "Start Decompression" adb shell "taskset 80 dd if=/dev/block/zram0 of=/dev/output_result bs=4096 count=131072 conv=fsync" echo "mm_stat:" adb shell "cat /sys/block/zram0/mm_stat" echo. Note: To ensure stable test results, it is best to lock the CPU frequency before executing the test. LZ4 supports dictionaries up to 64KB. Below are the test results for compression rates at various dictionary sizes: dict_size base patch 4 KB 156M/s 219M/s 8 KB 136M/s 217M/s 16KB 98M/s 214M/s 32KB 66M/s 225M/s 64KB 38M/s 224M/s When an LZ4 compression dictionary is enabled, compression speed is negatively impacted by the dictionary's size; larger dictionaries result in slower compression. This patch eliminates the influence of dictionary size on compression speed, ensuring consistent performance regardless of dictionary scale. Link: https://lkml.kernel.org/r/698181478c9c4b10aa21b4a847bdc706@honor.com Link: https://github.com/lz4/lz4?tab=readme-ov-file [1] Signed-off-by: gao xu Acked-by: Sergey Senozhatsky Cc: Jens Axboe Cc: Minchan Kim Cc: Suren Baghdasaryan Signed-off-by: Andrew Morton --- drivers/block/zram/backend_lz4.c | 29 ++++++++++++++++++++++++++--- 1 file changed, 26 insertions(+), 3 deletions(-) --- a/drivers/block/zram/backend_lz4.c~zram-optimize-lz4-dictionary-compression-performance-v2 +++ a/drivers/block/zram/backend_lz4.c @@ -14,13 +14,38 @@ struct lz4_ctx { static void lz4_release_params(struct zcomp_params *params) { + LZ4_stream_t *dict_stream = params->drv_data; + + params->drv_data = NULL; + if (!dict_stream) + return; + + kfree(dict_stream); } static int lz4_setup_params(struct zcomp_params *params) { + LZ4_stream_t *dict_stream; + int ret; + if (params->level == ZCOMP_PARAM_NOT_SET) params->level = LZ4_ACCELERATION_DEFAULT; + if (!params->dict || !params->dict_sz) + return 0; + + dict_stream = kzalloc_obj(*dict_stream, GFP_KERNEL); + if (!dict_stream) + return -ENOMEM; + + ret = LZ4_loadDict(dict_stream, + params->dict, params->dict_sz); + if (ret != params->dict_sz) { + kfree(dict_stream); + return -EINVAL; + } + params->drv_data = dict_stream; + return 0; } @@ -79,9 +104,7 @@ static int lz4_compress(struct zcomp_par zctx->mem); } else { /* Cstrm needs to be reset */ - ret = LZ4_loadDict(zctx->cstrm, params->dict, params->dict_sz); - if (ret != params->dict_sz) - return -EINVAL; + memcpy(zctx->cstrm, params->drv_data, sizeof(*zctx->cstrm)); ret = LZ4_compress_fast_continue(zctx->cstrm, req->src, req->dst, req->src_len, req->dst_len, params->level); _ Patches currently in -mm which might be from gaoxu2@honor.com are zram-use-statically-allocated-compression-algorithm-names.patch zram-optimize-lz4-dictionary-compression-performance-v2.patch