On Mon, Nov 09, 2015 at 07:09:25PM -0500, Waiman Long wrote:
> +static ssize_t qstat_read(struct file *file, char __user *user_buf,
> + size_t count, loff_t *ppos)
> +{
> + char buf[64];
> + int cpu, counter, len;
> + u64 stat = 0, kicks = 0;
> +
> + /*
> + * Get the counter ID stored in file->f_inode->i_private
> + */
> + if (!file->f_inode) {
> + WARN_ON_ONCE(1);
> + return -EBADF;
> + }
> + counter = (long)(file->f_inode->i_private);
> +
> + if (counter >= qstat_num)
> + return -EBADF;
> +
> + for_each_possible_cpu(cpu) {
> + stat += per_cpu(qstats[counter], cpu);
> + /*
> + * Need to sum additional counter for some of them
> + */
> + switch (counter) {
> +
> + case qstat_pv_latency_kick:
> + case qstat_pv_hash_hops:
> + kicks += per_cpu(qstats[qstat_pv_kick_unlock], cpu);
> + break;
> +
> + case qstat_pv_latency_wake:
> + kicks += per_cpu(qstats[qstat_pv_kick_wake], cpu);
> + break;
> + }
> + }
> +
> + if (counter == qstat_pv_hash_hops) {
> + /*
> + * Return a X.XX decimal number
> + */
> + len = snprintf(buf, sizeof(buf) - 1, "%llu.%02llu\n",
> + stat/kicks, ((stat%kicks)*100 + kicks/2)/kicks);
> + } else {
> + /*
> + * Round to the nearest ns
> + */
> + if ((counter == qstat_pv_latency_kick) ||
> + (counter == qstat_pv_latency_wake))
> + stat = kicks ? (stat + kicks/2)/kicks : 0;
> + len = snprintf(buf, sizeof(buf) - 1, "%llu\n", stat);
> + }
> +
> + return simple_read_from_buffer(user_buf, count, ppos, buf, len);
> +}
That doesn't work on 32bit.
---
--- a/kernel/locking/qspinlock_stat.h
+++ b/kernel/locking/qspinlock_stat.h
@@ -127,18 +127,25 @@ static ssize_t qstat_read(struct file *f
}
if (counter == qstat_pv_hash_hops) {
+ u64 frac;
+
+ frac = 100ULL * do_div(stat, kicks);
+ frac = DIV_ROUND_CLOSEST_ULL(frac, kicks);
+
/*
* Return a X.XX decimal number
*/
- len = snprintf(buf, sizeof(buf) - 1, "%llu.%02llu\n",
- stat/kicks, ((stat%kicks)*100 + kicks/2)/kicks);
+ len = snprintf(buf, sizeof(buf) - 1, "%llu.%02llu\n", stat,
frac);
} else {
/*
* Round to the nearest ns
*/
if ((counter == qstat_pv_latency_kick) ||
- (counter == qstat_pv_latency_wake))
- stat = kicks ? (stat + kicks/2)/kicks : 0;
+ (counter == qstat_pv_latency_wake)) {
+ stat = 0;
+ if (kicks)
+ stat = DIV_ROUND_CLOSEST_ULL(stat, kicks);
+ }
len = snprintf(buf, sizeof(buf) - 1, "%llu\n", stat);
}
--
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