From 65e5a0e18e5fb5bc6cfabd8ef4b9fc1c8569ba62 Mon Sep 17 00:00:00 2001 From: Daniel Drake Date: Thu, 7 Oct 2010 19:14:02 +0100 Subject: jffs2: Dynamically choose inocache hash size When JFFS2 is used for large volumes, the mount times are quite long. Increasing the hash size provides a significant speed boost on the OLPC XO-1 laptop. Add logic that dynamically selects a hash size based on the size of the medium. A 64mb medium will result in a hash size of 128, and a 512mb medium will result in a hash size of 1024. Signed-off-by: Daniel Drake Signed-off-by: David Woodhouse --- fs/jffs2/fs.c | 22 +++++++++++++++++++++- 1 file changed, 21 insertions(+), 1 deletion(-) (limited to 'fs/jffs2/fs.c') diff --git a/fs/jffs2/fs.c b/fs/jffs2/fs.c index 6b2964a..2701b37 100644 --- a/fs/jffs2/fs.c +++ b/fs/jffs2/fs.c @@ -478,6 +478,25 @@ struct inode *jffs2_new_inode (struct inode *dir_i, int mode, struct jffs2_raw_i return inode; } +static int calculate_inocache_hashsize(uint32_t flash_size) +{ + /* + * Pick a inocache hash size based on the size of the medium. + * Count how many megabytes we're dealing with, apply a hashsize twice + * that size, but rounding down to the usual big powers of 2. And keep + * to sensible bounds. + */ + + int size_mb = flash_size / 1024 / 1024; + int hashsize = (size_mb * 2) & ~0x3f; + + if (hashsize < INOCACHE_HASHSIZE_MIN) + return INOCACHE_HASHSIZE_MIN; + if (hashsize > INOCACHE_HASHSIZE_MAX) + return INOCACHE_HASHSIZE_MAX; + + return hashsize; +} int jffs2_do_fill_super(struct super_block *sb, void *data, int silent) { @@ -524,7 +543,8 @@ int jffs2_do_fill_super(struct super_block *sb, void *data, int silent) if (ret) return ret; - c->inocache_list = kcalloc(INOCACHE_HASHSIZE, sizeof(struct jffs2_inode_cache *), GFP_KERNEL); + c->inocache_hashsize = calculate_inocache_hashsize(c->flash_size); + c->inocache_list = kcalloc(c->inocache_hashsize, sizeof(struct jffs2_inode_cache *), GFP_KERNEL); if (!c->inocache_list) { ret = -ENOMEM; goto out_wbuf; -- cgit v1.1