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From: Timofey Titovets <nefelim4ag@gmail.com>
To: linux-btrfs@vger.kernel.org
Cc: Timofey Titovets <nefelim4ag@gmail.com>
Subject: [PATCH v7 4/6] Btrfs: heuristic add detection of repeated data patterns
Date: Fri, 25 Aug 2017 12:18:43 +0300	[thread overview]
Message-ID: <20170825091845.4120-5-nefelim4ag@gmail.com> (raw)
In-Reply-To: <20170825091845.4120-1-nefelim4ag@gmail.com>

Walk over data sample and use memcmp to detect
repeated data (like zeroed)

Signed-off-by: Timofey Titovets <nefelim4ag@gmail.com>
---
 fs/btrfs/heuristic.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/fs/btrfs/heuristic.c b/fs/btrfs/heuristic.c
index 5192e51ab81e..f1fa6e4f1c11 100644
--- a/fs/btrfs/heuristic.c
+++ b/fs/btrfs/heuristic.c
@@ -66,6 +66,19 @@ static struct list_head *heuristic_alloc_workspace(void)
 	return ERR_PTR(-ENOMEM);
 }

+static bool sample_repeated_patterns(struct workspace *ws)
+{
+	u32 i = 0;
+	u8 *p = ws->sample;
+
+	for (; i < ws->sample_size - READ_SIZE; i += READ_SIZE) {
+		if(memcpy(&p[i], &p[i + READ_SIZE], READ_SIZE))
+			return false;
+	}
+
+	return true;
+}
+
 static int heuristic(struct list_head *ws, struct inode *inode,
 		     u64 start, u64 end)
 {
@@ -115,6 +128,9 @@ static int heuristic(struct list_head *ws, struct inode *inode,

 	workspace->sample_size = b;

+	if (sample_repeated_patterns(workspace))
+		return 1;
+
 	memset(workspace->bucket, 0, sizeof(*workspace->bucket)*BUCKET_SIZE);

 	for (a = 0; a < workspace->sample_size; a++) {
--
2.14.1

  parent reply	other threads:[~2017-08-25  9:19 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-08-25  9:18 [PATCH v7 0/6] Btrfs: populate heuristic with code Timofey Titovets
2017-08-25  9:18 ` [PATCH v7 1/6] Btrfs: heuristic make use compression workspaces Timofey Titovets
2017-09-27 13:12   ` David Sterba
2017-08-25  9:18 ` [PATCH v7 2/6] Btrfs: heuristic workspace add bucket and sample items Timofey Titovets
2017-09-27 13:22   ` David Sterba
2017-08-25  9:18 ` [PATCH v7 3/6] Btrfs: implement heuristic sampling logic Timofey Titovets
2017-09-27 13:38   ` David Sterba
2017-08-25  9:18 ` Timofey Titovets [this message]
2017-09-27 13:47   ` [PATCH v7 4/6] Btrfs: heuristic add detection of repeated data patterns David Sterba
2017-08-25  9:18 ` [PATCH v7 5/6] Btrfs: heuristic add byte set calculation Timofey Titovets
2017-09-27 13:50   ` David Sterba
2017-08-25  9:18 ` [PATCH v7 6/6] Btrfs: heuristic add byte core " Timofey Titovets
2017-09-27 13:54   ` David Sterba
2017-09-27 13:56   ` David Sterba

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