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ext2load: increase read speed 

This patch dramatically drops the amount of time u-boot needs to read a
file from an ext2 partition.  On a typical 2 to 5 MB file (kernels and
initrds) it goes from tens of seconds to a couple seconds.

All we are doing here is grouping contiguous blocks into one read.

Boot tested on Globalscale Technologies Dreamplug (Kirkwood ARM SoC)
with three different files.  sha1sums were calculated in Linux
userspace, and then confirmed after ext2load.

Signed-off-by: Jason Cooper <u-boot@lakedaemon.net>
Tested-by: Eric Nelson <eric.nelson@boundarydevices.com>
Tested-by: Thierry Reding <thierry.reding@avionic-design.de>
This commit is contained in:
u-boot@lakedaemon.net 2012-03-28 04:37:11 +00:00 committed by Wolfgang Denk
parent 669df7e42d
commit 436da3cd23
1 changed files with 24 additions and 2 deletions
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26
fs/ext2/ext2fs.c
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@ -420,7 +420,6 @@ int ext2fs_read_file
if (blknr < 0) {
return (-1);
}
blknr = blknr << log2blocksize;
/* Last block. */
if (i == blockcnt - 1) {
@ -438,6 +437,29 @@ int ext2fs_read_file
blockend -= skipfirst;
}
/* grab middle blocks in one go */
if (i != pos / blocksize && i != blockcnt - 1 && blockcnt > 3) {
int oldblk = blknr;
int blocknxt;
while (i < blockcnt - 1) {
blocknxt = ext2fs_read_block(node, i + 1);
if (blocknxt == (oldblk + 1)) {
oldblk = blocknxt;
i++;
} else {
blocknxt = ext2fs_read_block(node, i);
break;
}
}
if (oldblk == blknr)
blockend = blocksize;
else
blockend = (1 + blocknxt - blknr) * blocksize;
}
blknr = blknr << log2blocksize;
/* If the block number is 0 this block is not stored on disk but
is zero filled instead. */
if (blknr) {
@ -450,7 +472,7 @@ int ext2fs_read_file
} else {
memset (buf, 0, blocksize - skipfirst);
}
buf += blocksize - skipfirst;
buf += blockend - skipfirst;
}
return (len);
}