From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steven Whitehouse Date: Thu, 18 Oct 2012 14:16:44 +0100 Subject: [Cluster-devel] [GFS2 PATCH] GFS2: Speed up gfs2_rbm_from_block In-Reply-To: <248019210.19530061.1350486363108.JavaMail.root@redhat.com> References: <248019210.19530061.1350486363108.JavaMail.root@redhat.com> Message-ID: <1350566204.2708.79.camel@menhir> List-Id: To: cluster-devel.redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Hi, On Wed, 2012-10-17 at 11:06 -0400, Bob Peterson wrote: > Hi, > > 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. This speeds up the function significantly. > It would be a good plan to include the timings that you showed me yesterday in the patch description to show the improvement this gives. > Regards, > > Bob Peterson > Red Hat File Systems > > Signed-off-by: Bob Peterson > --- > diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h > index 3d469d3..24bb0b8 100644 > --- 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 e443966..0e3554e 100644 > --- 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 43d1a20..7635500 100644 > --- a/fs/gfs2/rgrp.c > +++ b/fs/gfs2/rgrp.c > @@ -250,23 +250,23 @@ 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; This test was intended to check for underflow, i.e. that the block number was less than rd_data0. I think it would be a good plan to retain such a test even though we should not see any blocks outside of the current bitmap. Otherwise, it looks good, Steve. > 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)(block - rbm->rgd->rd_data0); > + /* 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; > } > >