From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f193.google.com ([209.85.128.193]:36280 "EHLO mail-wr0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753323AbdHTSL2 (ORCPT ); Sun, 20 Aug 2017 14:11:28 -0400 Received: by mail-wr0-f193.google.com with SMTP id f8so9040499wrf.3 for ; Sun, 20 Aug 2017 11:11:28 -0700 (PDT) From: Timofey Titovets To: linux-btrfs@vger.kernel.org Cc: Timofey Titovets Subject: [PATCH v4 2/3] Btrfs: heuristic add byte set calculation Date: Sun, 20 Aug 2017 21:11:15 +0300 Message-Id: <20170820181116.5131-3-nefelim4ag@gmail.com> In-Reply-To: <20170820181116.5131-1-nefelim4ag@gmail.com> References: <20170820181116.5131-1-nefelim4ag@gmail.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: Calculate byte set size for data sample: Calculate how many unique bytes has been in sample By count all bytes in bucket with count > 0 If byte set low (~25%), data are easily compressible Signed-off-by: Timofey Titovets --- fs/btrfs/compression.c | 27 +++++++++++++++++++++++++++ fs/btrfs/compression.h | 1 + 2 files changed, 28 insertions(+) diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c index c078c8d8c034..fe26a44bcc9b 100644 --- a/fs/btrfs/compression.c +++ b/fs/btrfs/compression.c @@ -1048,6 +1048,27 @@ int btrfs_decompress_buf2page(const char *buf, unsigned long buf_start, return 1; } +static inline int byte_set_size(const struct heuristic_bucket_item *bucket) +{ + int a = 0; + int byte_set_size = 0; + + for (; a < BTRFS_HEURISTIC_BYTE_SET_THRESHOLD; a++) { + if (bucket[a].count > 0) + byte_set_size++; + } + + for (; a < BTRFS_HEURISTIC_BUCKET_SIZE; a++) { + if (bucket[a].count > 0) { + byte_set_size++; + if (byte_set_size > BTRFS_HEURISTIC_BYTE_SET_THRESHOLD) + return byte_set_size; + } + } + + return byte_set_size; +} + /* * Compression heuristic. * @@ -1096,6 +1117,12 @@ int btrfs_compress_heuristic(struct inode *inode, u64 start, u64 end) index++; } + a = byte_set_size(bucket); + if (a > BTRFS_HEURISTIC_BYTE_SET_THRESHOLD) { + ret = 1; + goto out; + } + out: kfree(bucket); return ret; diff --git a/fs/btrfs/compression.h b/fs/btrfs/compression.h index e0421705b80b..07e3d0652e62 100644 --- a/fs/btrfs/compression.h +++ b/fs/btrfs/compression.h @@ -135,6 +135,7 @@ struct heuristic_bucket_item { #define BTRFS_HEURISTIC_READ_SIZE 16 #define BTRFS_HEURISTIC_ITER_OFFSET 256 #define BTRFS_HEURISTIC_BUCKET_SIZE 256 +#define BTRFS_HEURISTIC_BYTE_SET_THRESHOLD 64 int btrfs_compress_heuristic(struct inode *inode, u64 start, u64 end); -- 2.14.1