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| author | Mingming Cao <cmm@us.ibm.com> | 2008-07-12 01:27:31 +0200 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2008-07-12 01:27:31 +0200 |
| commit | e8ced39d5e8911c662d4d69a342b9d053eaaac4e (patch) | |
| tree | cd4d643bfbd37c67ff9bd2feff2c0b477a56f117 /lib/percpu_counter.c | |
| parent | ext4: Add delayed allocation support in data=writeback mode (diff) | |
| download | linux-e8ced39d5e8911c662d4d69a342b9d053eaaac4e.tar.xz linux-e8ced39d5e8911c662d4d69a342b9d053eaaac4e.zip | |
percpu_counter: new function percpu_counter_sum_and_set
Delayed allocation need to check free blocks at every write time.
percpu_counter_read_positive() is not quit accurate. delayed
allocation need a more accurate accounting, but using
percpu_counter_sum_positive() is frequently is quite expensive.
This patch added a new function to update center counter when sum
per-cpu counter, to increase the accurate rate for next
percpu_counter_read() and require less calling expensive
percpu_counter_sum().
Signed-off-by: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Diffstat (limited to 'lib/percpu_counter.c')
| -rw-r--r-- | lib/percpu_counter.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/lib/percpu_counter.c b/lib/percpu_counter.c index 119174494cb5..4a8ba4bf5f6f 100644 --- a/lib/percpu_counter.c +++ b/lib/percpu_counter.c @@ -52,7 +52,7 @@ EXPORT_SYMBOL(__percpu_counter_add); * Add up all the per-cpu counts, return the result. This is a more accurate * but much slower version of percpu_counter_read_positive() */ -s64 __percpu_counter_sum(struct percpu_counter *fbc) +s64 __percpu_counter_sum(struct percpu_counter *fbc, int set) { s64 ret; int cpu; @@ -62,7 +62,12 @@ s64 __percpu_counter_sum(struct percpu_counter *fbc) for_each_online_cpu(cpu) { s32 *pcount = per_cpu_ptr(fbc->counters, cpu); ret += *pcount; + if (set) + *pcount = 0; } + if (set) + fbc->count = ret; + spin_unlock(&fbc->lock); return ret; } |