Re: [PATCH 1/2] scsi: ufs: Introduce hba performance monitor sysfs nodes

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Hi Daejun,

On 2021-04-06 12:11, Daejun Park wrote:
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?

lat_min is already 0. What is the benefit of setting lat_max to KTIME_MAX?

I think lat_sum should be 0 at this point.

lat_sum is already 0 at this point, what is the problem?


+        }
+
+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?

I am expecting "now" keeps increasing and use it to update m->busy_start_s, but if I use lrbp->compl_time_stamp to do that, below line ktime_sub() may give me an unexpected value as lrbp->compl_time_stamp may be smaller than m->busy_start_ts, because the actual requests are not completed by the device in the exact same ordering as the bits set in hba->outstanding_tasks, but driver
is completing them from bit 0 to bit 31 in ascending order.


+                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.

I don't quite get it, can you show me the code sample?

Thanks,
Can Guo


+
+                m->nr_queued[dir]--;
+                /* Push forward the busy start of monitor */
+                m->busy_start_ts[dir] = now;
+        }
+}

Thanks,
Daejun



[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Index of Archives]     [SCSI Target Devel]     [Linux SCSI Target Infrastructure]     [Kernel Newbies]     [IDE]     [Security]     [Git]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Linux ATA RAID]     [Linux IIO]     [Samba]     [Device Mapper]

  Powered by Linux