From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail.phycard.co.uk ([217.6.246.34] helo=root.phytec.de) by merlin.infradead.org with esmtp (Exim 4.76 #1 (Red Hat Linux)) id 1SUDrI-0004GL-AR for barebox@lists.infradead.org; Tue, 15 May 2012 09:15:58 +0000 Received: from idefix.phytec.de (idefix.phytec.de [172.16.0.10]) by root.phytec.de (Postfix) with ESMTP id 24811BF0D9 for ; Tue, 15 May 2012 11:15:48 +0200 (CEST) From: Jan Weitzel Date: Tue, 15 May 2012 11:15:46 +0200 Message-Id: <1337073346-4256-1-git-send-email-j.weitzel@phytec.de> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: barebox-bounces@lists.infradead.org Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: [RFC] ramfs: rember last accessed chunk To: barebox@lists.infradead.org Writing big files takes longer and longer because of the chunk list By storing a pointer of the recent used chunk in the inode, access times are improved. Testet on with tftp 10M: OMAP4 chunk size 4096: 12244ms 8192: 4239ms patched 2647ms 2785ms i.MX35 chunk size 8192: 7225ms patched 2691ms No impact on much smaller files seen Signed-off-by: Jan Weitzel --- fs/ramfs.c | 46 ++++++++++++++++++++++++++++++++++++---------- 1 files changed, 36 insertions(+), 10 deletions(-) diff --git a/fs/ramfs.c b/fs/ramfs.c index 83ab6df..5c7410b 100644 --- a/fs/ramfs.c +++ b/fs/ramfs.c @@ -48,6 +48,10 @@ struct ramfs_inode { ulong size; struct ramfs_chunk *data; + + /* Points to recently used chunk */ + int recent_chunk; + struct ramfs_chunk *recent_chunkp; }; struct ramfs_priv { @@ -297,6 +301,34 @@ static int ramfs_close(struct device_d *dev, FILE *f) return 0; } +static struct ramfs_chunk *ramfs_find_chunk(struct ramfs_inode *node, int chunk) +{ + struct ramfs_chunk *data; + int left = chunk; + + if (chunk == 0) + return node->data; + + if (node->recent_chunk == chunk) + return node->recent_chunkp; + + if (node->recent_chunk < chunk && node->recent_chunk != 0) { + /* Start at last known chunk */ + data = node->recent_chunkp; + left -= node->recent_chunk; + } else + /* Start at first chunk */ + data = node->data; + + while (left--) + data = data->next; + + node->recent_chunkp = data; + node->recent_chunk = chunk; + + return data; +} + static int ramfs_read(struct device_d *_dev, FILE *f, void *buf, size_t insize) { struct ramfs_inode *node = (struct ramfs_inode *)f->inode; @@ -311,11 +343,7 @@ static int ramfs_read(struct device_d *_dev, FILE *f, void *buf, size_t insize) debug("%s: reading from chunk %d\n", __FUNCTION__, chunk); /* Position ourself in stream */ - data = node->data; - while (chunk) { - data = data->next; - chunk--; - } + data = ramfs_find_chunk(node, chunk); ofs = f->pos % CHUNK_SIZE; /* Read till end of current chunk */ @@ -364,11 +392,7 @@ static int ramfs_write(struct device_d *_dev, FILE *f, const void *buf, size_t i debug("%s: writing to chunk %d\n", __FUNCTION__, chunk); /* Position ourself in stream */ - data = node->data; - while (chunk) { - data = data->next; - chunk--; - } + data = ramfs_find_chunk(node, chunk); ofs = f->pos % CHUNK_SIZE; /* Write till end of current chunk */ @@ -429,6 +453,8 @@ static int ramfs_truncate(struct device_d *dev, FILE *f, ulong size) ramfs_put_chunk(data); data = tmp; } + if (node->recent_chunk > newchunks) + node->recent_chunk = 0; } if (newchunks > oldchunks) { -- 1.7.0.4 _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox