GFS2: Speed up gfs2_rbm_from_block (a68a0a35) · Commits · 戴 / test

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>

fs/gfs2/incore.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -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];

fs/gfs2/ops_fstype.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -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 */

fs/gfs2/rgrp.c

+12 −9

Original line number	Diff line number	Diff line
		@@ -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;
		}

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