*/
#include <linux/cgroup.h>
-#include <linux/u64_stats_sync.h>
+#include <linux/percpu_counter.h>
#include <linux/seq_file.h>
#include <linux/radix-tree.h>
#include <linux/blkdev.h>
#include <linux/atomic.h>
+/* percpu_counter batch for blkg_[rw]stats, per-cpu drift doesn't matter */
+#define BLKG_STAT_CPU_BATCH (INT_MAX / 2)
+
/* Max limits for throttle policy */
#define THROTL_IOPS_MAX UINT_MAX
/*
* blkg_[rw]stat->aux_cnt is excluded for local stats but included for
- * recursive. Used to carry stats of dead children.
+ * recursive. Used to carry stats of dead children, and, for blkg_rwstat,
+ * to carry result values from read and sum operations.
*/
struct blkg_stat {
- struct u64_stats_sync syncp;
- uint64_t cnt;
+ struct percpu_counter cpu_cnt;
atomic64_t aux_cnt;
};
struct blkg_rwstat {
- struct u64_stats_sync syncp;
- uint64_t cnt[BLKG_RWSTAT_NR];
+ struct percpu_counter cpu_cnt[BLKG_RWSTAT_NR];
atomic64_t aux_cnt[BLKG_RWSTAT_NR];
};
#define blk_queue_for_each_rl(rl, q) \
for ((rl) = &(q)->root_rl; (rl); (rl) = __blk_queue_next_rl((rl), (q)))
-static inline void blkg_stat_init(struct blkg_stat *stat)
+static inline int blkg_stat_init(struct blkg_stat *stat, gfp_t gfp)
{
- u64_stats_init(&stat->syncp);
+ int ret;
+
+ ret = percpu_counter_init(&stat->cpu_cnt, 0, gfp);
+ if (ret)
+ return ret;
+
atomic64_set(&stat->aux_cnt, 0);
+ return 0;
+}
+
+static inline void blkg_stat_exit(struct blkg_stat *stat)
+{
+ percpu_counter_destroy(&stat->cpu_cnt);
}
/**
* @stat: target blkg_stat
* @val: value to add
*
- * Add @val to @stat. The caller is responsible for synchronizing calls to
- * this function.
+ * Add @val to @stat. The caller must ensure that IRQ on the same CPU
+ * don't re-enter this function for the same counter.
*/
static inline void blkg_stat_add(struct blkg_stat *stat, uint64_t val)
{
- u64_stats_update_begin(&stat->syncp);
- stat->cnt += val;
- u64_stats_update_end(&stat->syncp);
+ __percpu_counter_add(&stat->cpu_cnt, val, BLKG_STAT_CPU_BATCH);
}
/**
* blkg_stat_read - read the current value of a blkg_stat
* @stat: blkg_stat to read
- *
- * Read the current value of @stat. The returned value doesn't include the
- * aux count. This function can be called without synchroniztion and takes
- * care of u64 atomicity.
*/
static inline uint64_t blkg_stat_read(struct blkg_stat *stat)
{
- unsigned int start;
- uint64_t v;
-
- do {
- start = u64_stats_fetch_begin_irq(&stat->syncp);
- v = stat->cnt;
- } while (u64_stats_fetch_retry_irq(&stat->syncp, start));
-
- return v;
+ return percpu_counter_sum_positive(&stat->cpu_cnt);
}
/**
*/
static inline void blkg_stat_reset(struct blkg_stat *stat)
{
- stat->cnt = 0;
+ percpu_counter_set(&stat->cpu_cnt, 0);
atomic64_set(&stat->aux_cnt, 0);
}
&to->aux_cnt);
}
-static inline void blkg_rwstat_init(struct blkg_rwstat *rwstat)
+static inline int blkg_rwstat_init(struct blkg_rwstat *rwstat, gfp_t gfp)
{
- int i;
+ int i, ret;
+
+ for (i = 0; i < BLKG_RWSTAT_NR; i++) {
+ ret = percpu_counter_init(&rwstat->cpu_cnt[i], 0, gfp);
+ if (ret) {
+ while (--i >= 0)
+ percpu_counter_destroy(&rwstat->cpu_cnt[i]);
+ return ret;
+ }
+ atomic64_set(&rwstat->aux_cnt[i], 0);
+ }
+ return 0;
+}
- u64_stats_init(&rwstat->syncp);
+static inline void blkg_rwstat_exit(struct blkg_rwstat *rwstat)
+{
+ int i;
for (i = 0; i < BLKG_RWSTAT_NR; i++)
- atomic64_set(&rwstat->aux_cnt[i], 0);
+ percpu_counter_destroy(&rwstat->cpu_cnt[i]);
}
/**
static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat,
int rw, uint64_t val)
{
- u64_stats_update_begin(&rwstat->syncp);
+ struct percpu_counter *cnt;
if (rw & REQ_WRITE)
- rwstat->cnt[BLKG_RWSTAT_WRITE] += val;
+ cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_WRITE];
else
- rwstat->cnt[BLKG_RWSTAT_READ] += val;
+ cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_READ];
+
+ __percpu_counter_add(cnt, val, BLKG_STAT_CPU_BATCH);
+
if (rw & REQ_SYNC)
- rwstat->cnt[BLKG_RWSTAT_SYNC] += val;
+ cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_SYNC];
else
- rwstat->cnt[BLKG_RWSTAT_ASYNC] += val;
+ cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_ASYNC];
- u64_stats_update_end(&rwstat->syncp);
+ __percpu_counter_add(cnt, val, BLKG_STAT_CPU_BATCH);
}
/**
* blkg_rwstat_read - read the current values of a blkg_rwstat
* @rwstat: blkg_rwstat to read
*
- * Read the current snapshot of @rwstat and return it as the return value.
- * This function can be called without synchronization and takes care of
- * u64 atomicity.
+ * Read the current snapshot of @rwstat and return it in the aux counts.
*/
static inline struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat)
{
- unsigned int start;
- struct blkg_rwstat tmp;
-
- do {
- start = u64_stats_fetch_begin_irq(&rwstat->syncp);
- tmp = *rwstat;
- } while (u64_stats_fetch_retry_irq(&rwstat->syncp, start));
+ struct blkg_rwstat result;
+ int i;
- return tmp;
+ for (i = 0; i < BLKG_RWSTAT_NR; i++)
+ atomic64_set(&result.aux_cnt[i],
+ percpu_counter_sum_positive(&rwstat->cpu_cnt[i]));
+ return result;
}
/**
{
struct blkg_rwstat tmp = blkg_rwstat_read(rwstat);
- return tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE];
+ return atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_READ]) +
+ atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_WRITE]);
}
/**
{
int i;
- memset(rwstat->cnt, 0, sizeof(rwstat->cnt));
-
- for (i = 0; i < BLKG_RWSTAT_NR; i++)
+ for (i = 0; i < BLKG_RWSTAT_NR; i++) {
+ percpu_counter_set(&rwstat->cpu_cnt[i], 0);
atomic64_set(&rwstat->aux_cnt[i], 0);
+ }
}
/**
int i;
for (i = 0; i < BLKG_RWSTAT_NR; i++)
- atomic64_add(v.cnt[i] + atomic64_read(&from->aux_cnt[i]),
+ atomic64_add(atomic64_read(&v.aux_cnt[i]) +
+ atomic64_read(&from->aux_cnt[i]),
&to->aux_cnt[i]);
}
projects / linux-2.6-block.git / blobdiff