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>

diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
index 3d469d37345ebfad798578830b9d768a59c6a35c..24bb0b857860fbf2a0778d309edb85bf17c50a86 100644 (file)
--- a/fs/gfs2/incore.h
+++ b/fs/gfs2/incore.h
@@ -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];

diff --git a/fs/gfs2/ops_fstype.c b/fs/gfs2/ops_fstype.c
index e443966c810697e50f71b37afb807db62828335f..0e3554edb8f25d2f5d82932294eca6b5b4d54020 100644 (file)
--- a/fs/gfs2/ops_fstype.c
+++ b/fs/gfs2/ops_fstype.c
@@ -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 */
 

diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index 38fe18f2f055af2e5e842573a475e7b6836bb940..669b89b95ccc35b3794bd78301bcf9f741cf429b 100644 (file)
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -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;
 }