Commit 05220535 authored Jan 11, 2008 by Bob Peterson Committed by Steven Whitehouse Jan 25, 2008

[GFS2] gfs2_alloc_required performance

This is a small I/O performance enhancement to gfs2. (Actually, it is a rework of
an earlier version I got wrong). The idea here is to check if the write extends
past the last block in the file. If so, the function can save itself a lot of
time and trouble because it knows an allocate will be required. Benchmarks like
iozone should see better performance.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

parent 598278bd

fs/gfs2/bmap.c

+5 −0

Original line number	Diff line number	Diff line
		@@ -1224,6 +1224,11 @@ int gfs2_write_alloc_required(struct gfs2_inode *ip, u64 offset,
		unsigned int shift = sdp->sd_sb.sb_bsize_shift;
		lblock = offset >> shift;
		lblock_stop = (offset + len + sdp->sd_sb.sb_bsize - 1) >> shift;
		if (lblock_stop > ip->i_di.di_blocks) { /* writing past the
		last block */
		*alloc_required = 1;
		return 0;
		}
		}

		for (; lblock < lblock_stop; lblock += extlen) {

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