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authorAndrew Morton <akpm@osdl.org>2006-03-07 21:55:31 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-03-08 14:14:01 -0800
commite2bab3d92486fb781f4d06f56339264ed1492392 (patch)
tree0295e1ed29794a8e804c4e28a3ea9e72777e533b /mm/swap.c
parentb884e25784f62a1c740d2e4c1ce19cb89644e986 (diff)
downloadlwn-e2bab3d92486fb781f4d06f56339264ed1492392.tar.gz
lwn-e2bab3d92486fb781f4d06f56339264ed1492392.zip
[PATCH] percpu_counter_sum()
Implement percpu_counter_sum(). This is a more accurate but slower version of percpu_counter_read_positive(). We need this for Alex's speedup-ext3_statfs patch and for the nr_file accounting fix. Otherwise these things would be too inaccurate on large CPU counts. Cc: Ravikiran G Thirumalai <kiran@scalex86.org> Cc: Alex Tomas <alex@clusterfs.com> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'mm/swap.c')
-rw-r--r--mm/swap.c25
1 files changed, 23 insertions, 2 deletions
diff --git a/mm/swap.c b/mm/swap.c
index cce3dda59c59..e9ec06d845e8 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -489,13 +489,34 @@ void percpu_counter_mod(struct percpu_counter *fbc, long amount)
if (count >= FBC_BATCH || count <= -FBC_BATCH) {
spin_lock(&fbc->lock);
fbc->count += count;
+ *pcount = 0;
spin_unlock(&fbc->lock);
- count = 0;
+ } else {
+ *pcount = count;
}
- *pcount = count;
put_cpu();
}
EXPORT_SYMBOL(percpu_counter_mod);
+
+/*
+ * Add up all the per-cpu counts, return the result. This is a more accurate
+ * but much slower version of percpu_counter_read_positive()
+ */
+long percpu_counter_sum(struct percpu_counter *fbc)
+{
+ long ret;
+ int cpu;
+
+ spin_lock(&fbc->lock);
+ ret = fbc->count;
+ for_each_cpu(cpu) {
+ long *pcount = per_cpu_ptr(fbc->counters, cpu);
+ ret += *pcount;
+ }
+ spin_unlock(&fbc->lock);
+ return ret < 0 ? 0 : ret;
+}
+EXPORT_SYMBOL(percpu_counter_sum);
#endif
/*