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GFS2: Speed up gfs2_rbm_from_block 

This patch is a rewrite of function gfs2_rbm_from_block. Rather than
looping to find the right bitmap, the code now does a few simple
math calculations.

I compared the performance of both algorithms side by side and the new
algorithm is noticeably faster. Sample instrumentation output from a
"fast" machine:

5 million calls: millisec spent: Orig: 166 New: 113
5 million calls: millisec spent: Orig: 189 New: 114

In addition, I ran postmark (on a somewhat slowr CPU) before the after
the new algorithm was put in place and postmark showed a decent
improvement:

Before the new algorithm:
-------------------------
Time:
	645 seconds total
	584 seconds of transactions (171 per second)

Files:
	150087 created (232 per second)
		Creation alone: 100000 files (2083 per second)
		Mixed with transactions: 50087 files (85 per second)
	49995 read (85 per second)
	49991 appended (85 per second)
	150087 deleted (232 per second)
		Deletion alone: 100174 files (7705 per second)
		Mixed with transactions: 49913 files (85 per second)

Data:
	273.42 megabytes read (434.08 kilobytes per second)
	852.13 megabytes written (1.32 megabytes per second)

With the new algorithm:
-----------------------
Time:
	599 seconds total
	530 seconds of transactions (188 per second)

Files:
	150087 created (250 per second)
		Creation alone: 100000 files (1886 per second)
		Mixed with transactions: 50087 files (94 per second)
	49995 read (94 per second)
	49991 appended (94 per second)
	150087 deleted (250 per second)
		Deletion alone: 100174 files (6260 per second)
		Mixed with transactions: 49913 files (94 per second)

Data:
	273.42 megabytes read (467.42 kilobytes per second)
	852.13 megabytes written (1.42 megabytes per second)

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
This commit is contained in:
Bob Peterson 2012-10-19 08:32:51 -04:00 committed by Steven Whitehouse
parent 8eae1ca003
commit a68a0a352a
3 changed files with 16 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
fs/gfs2/incore.h
View File

@ -621,6 +621,7 @@ struct gfs2_sbd {
u32 sd_hash_bsize_shift;
u32 sd_hash_ptrs; /* Number of pointers in a hash block */
u32 sd_qc_per_block;
u32 sd_blocks_per_bitmap;
u32 sd_max_dirres; /* Max blocks needed to add a directory entry */
u32 sd_max_height; /* Max height of a file's metadata tree */
u64 sd_heightsize[GFS2_MAX_META_HEIGHT + 1];

3
fs/gfs2/ops_fstype.c
View File

@ -278,6 +278,9 @@ static int gfs2_read_sb(struct gfs2_sbd *sdp, int silent)
sdp->sd_qc_per_block = (sdp->sd_sb.sb_bsize -
sizeof(struct gfs2_meta_header)) /
sizeof(struct gfs2_quota_change);
sdp->sd_blocks_per_bitmap = (sdp->sd_sb.sb_bsize -
sizeof(struct gfs2_meta_header))
* GFS2_NBBY; /* not the rgrp bitmap, subsequent bitmaps only */
/* Compute maximum reservation required to add a entry to a directory */

21
fs/gfs2/rgrp.c
View File

@ -251,22 +251,25 @@ static u32 gfs2_bitfit(const u8 *buf, const unsigned int len,
static int gfs2_rbm_from_block(struct gfs2_rbm *rbm, u64 block)
{
u64 rblock = block - rbm->rgd->rd_data0;
u32 goal = (u32)rblock;
int x;
u32 x;
if (WARN_ON_ONCE(rblock > UINT_MAX))
return -EINVAL;
if (block >= rbm->rgd->rd_data0 + rbm->rgd->rd_data)
return -E2BIG;
for (x = 0; x < rbm->rgd->rd_length; x++) {
rbm->bi = rbm->rgd->rd_bits + x;
if (goal < (rbm->bi->bi_start + rbm->bi->bi_len) * GFS2_NBBY) {
rbm->offset = goal - (rbm->bi->bi_start * GFS2_NBBY);
break;
}
}
rbm->bi = rbm->rgd->rd_bits;
rbm->offset = (u32)(rblock);
/* Check if the block is within the first block */
if (rbm->offset < (rbm->bi->bi_start + rbm->bi->bi_len) * GFS2_NBBY)
return 0;
/* Adjust for the size diff between gfs2_meta_header and gfs2_rgrp */
rbm->offset += (sizeof(struct gfs2_rgrp) -
sizeof(struct gfs2_meta_header)) * GFS2_NBBY;
x = rbm->offset / rbm->rgd->rd_sbd->sd_blocks_per_bitmap;
rbm->offset -= x * rbm->rgd->rd_sbd->sd_blocks_per_bitmap;
rbm->bi += x;
return 0;
}