GFS2: Set of distributed preferences for rgrps
This patch tries to use the journal numbers to evenly distribute
which node prefers which resource group for block allocations. This
is to help performance.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index 7474c41..f4e4a0c 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -936,7 +936,7 @@
rgd->rd_gl->gl_vm.start = rgd->rd_addr * bsize;
rgd->rd_gl->gl_vm.end = rgd->rd_gl->gl_vm.start + (rgd->rd_length * bsize) - 1;
rgd->rd_rgl = (struct gfs2_rgrp_lvb *)rgd->rd_gl->gl_lksb.sb_lvbptr;
- rgd->rd_flags &= ~GFS2_RDF_UPTODATE;
+ rgd->rd_flags &= ~(GFS2_RDF_UPTODATE | GFS2_RDF_PREFERRED);
if (rgd->rd_data > sdp->sd_max_rg_data)
sdp->sd_max_rg_data = rgd->rd_data;
spin_lock(&sdp->sd_rindex_spin);
@@ -955,6 +955,36 @@
}
/**
+ * set_rgrp_preferences - Run all the rgrps, selecting some we prefer to use
+ * @sdp: the GFS2 superblock
+ *
+ * The purpose of this function is to select a subset of the resource groups
+ * and mark them as PREFERRED. We do it in such a way that each node prefers
+ * to use a unique set of rgrps to minimize glock contention.
+ */
+static void set_rgrp_preferences(struct gfs2_sbd *sdp)
+{
+ struct gfs2_rgrpd *rgd, *first;
+ int i;
+
+ /* Skip an initial number of rgrps, based on this node's journal ID.
+ That should start each node out on its own set. */
+ rgd = gfs2_rgrpd_get_first(sdp);
+ for (i = 0; i < sdp->sd_lockstruct.ls_jid; i++)
+ rgd = gfs2_rgrpd_get_next(rgd);
+ first = rgd;
+
+ do {
+ rgd->rd_flags |= GFS2_RDF_PREFERRED;
+ for (i = 0; i < sdp->sd_journals; i++) {
+ rgd = gfs2_rgrpd_get_next(rgd);
+ if (rgd == first)
+ break;
+ }
+ } while (rgd != first);
+}
+
+/**
* gfs2_ri_update - Pull in a new resource index from the disk
* @ip: pointer to the rindex inode
*
@@ -973,6 +1003,8 @@
if (error < 0)
return error;
+ set_rgrp_preferences(sdp);
+
sdp->sd_rindex_uptodate = 1;
return 0;
}
@@ -1891,6 +1923,25 @@
}
/**
+ * fast_to_acquire - determine if a resource group will be fast to acquire
+ *
+ * If this is one of our preferred rgrps, it should be quicker to acquire,
+ * because we tried to set ourselves up as dlm lock master.
+ */
+static inline int fast_to_acquire(struct gfs2_rgrpd *rgd)
+{
+ struct gfs2_glock *gl = rgd->rd_gl;
+
+ if (gl->gl_state != LM_ST_UNLOCKED && list_empty(&gl->gl_holders) &&
+ !test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags) &&
+ !test_bit(GLF_DEMOTE, &gl->gl_flags))
+ return 1;
+ if (rgd->rd_flags & GFS2_RDF_PREFERRED)
+ return 1;
+ return 0;
+}
+
+/**
* gfs2_inplace_reserve - Reserve space in the filesystem
* @ip: the inode to reserve space for
* @ap: the allocation parameters
@@ -1932,10 +1983,15 @@
rg_locked = 0;
if (skip && skip--)
goto next_rgrp;
- if (!gfs2_rs_active(rs) && (loops < 2) &&
- gfs2_rgrp_used_recently(rs, 1000) &&
- gfs2_rgrp_congested(rs->rs_rbm.rgd, loops))
- goto next_rgrp;
+ if (!gfs2_rs_active(rs)) {
+ if (loops == 0 &&
+ !fast_to_acquire(rs->rs_rbm.rgd))
+ goto next_rgrp;
+ if ((loops < 2) &&
+ gfs2_rgrp_used_recently(rs, 1000) &&
+ gfs2_rgrp_congested(rs->rs_rbm.rgd, loops))
+ goto next_rgrp;
+ }
error = gfs2_glock_nq_init(rs->rs_rbm.rgd->rd_gl,
LM_ST_EXCLUSIVE, flags,
&rs->rs_rgd_gh);