Hi Can Guo,
> +static ssize_t monitor_enable_store(struct device *dev,
> + struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + struct ufs_hba *hba = dev_get_drvdata(dev);
> + unsigned long value, flags;
> +
> + if (kstrtoul(buf, 0, &value))
> + return -EINVAL;
> +
> + value = !!value;
> + spin_lock_irqsave(hba->host->host_lock, flags);
> + if (value == hba->monitor.enabled)
> + goto out_unlock;
> +
> + if (!value) {
> + memset(&hba->monitor, 0, sizeof(hba->monitor));
> + } else {
> + hba->monitor.enabled = true;
> + hba->monitor.enabled_ts = ktime_get();
How about setting lat_max to and lat_min to KTIME_MAX and 0?
I think lat_sum should be 0 at this point.
> + }
> +
> +out_unlock:
> + spin_unlock_irqrestore(hba->host->host_lock, flags);
> + return count;
> +}
> +static void ufshcd_update_monitor(struct ufs_hba *hba, struct ufshcd_lrb *lrbp)
> +{
> + int dir = ufshcd_monitor_opcode2dir(*lrbp->cmd->cmnd);
> +
> + if (dir >= 0 && hba->monitor.nr_queued[dir] > 0) {
> + struct request *req = lrbp->cmd->request;
> + struct ufs_hba_monitor *m = &hba->monitor;
> + ktime_t now, inc, lat;
> +
> + now = ktime_get();
How about using lrbp->compl_time_stamp instead of getting new value?
> + inc = ktime_sub(now, m->busy_start_ts[dir]);
> + m->total_busy[dir] = ktime_add(m->total_busy[dir], inc);
> + m->nr_sec_rw[dir] += blk_rq_sectors(req);
> +
> + /* Update latencies */
> + m->nr_req[dir]++;
> + lat = ktime_sub(now, lrbp->issue_time_stamp);
> + m->lat_sum[dir] += lat;
> + if (m->lat_max[dir] < lat || !m->lat_max[dir])
> + m->lat_max[dir] = lat;
> + if (m->lat_min[dir] > lat || !m->lat_min[dir])
> + m->lat_min[dir] = lat;
This if statement can be shorted, by setting lat_max / lat_min as default value.
> +
> + m->nr_queued[dir]--;
> + /* Push forward the busy start of monitor */
> + m->busy_start_ts[dir] = now;
> + }
> +}
Thanks,
Daejun
