iocost_monitor: improve it by adding iocg wait_ms

The iocg can have three throttled metrics: wait, debt, delay. This patch
add missing wait_ms to IocgStat to show the latest wait_ms of iocg.

As we are here, group iocg usage percents "inflt%" and "usage%" together,
and group iocg throttled metrics "wait", "debt" and "delay" together.

Effect after changes:

nvme0n1 RUN  per=50.0ms cur_per=177105.713:v1053528.587 busy= +0 vrate=135.00%:270.00% params=ssd_dfl(CQ)
                          active    weight      hweight% inflt% usage%    wait    debt   delay
InterfererGroup0             *   100/  100  54.28/  9.09   0.34  24.07    0.00    0.00    0.00
interfered                   *    84/ 1000  45.72/ 90.91   0.48  41.09    0.00    0.00    0.00

Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230804065039.8885-3-chengming.zhou@linux.dev
Signed-off-by: Jens Axboe <axboe@kernel.dk>

tools/cgroup/iocost_monitor.py

@@ -138,7 +138,7 @@ class IocStat:
 
     def table_header_str(self):
         return f'{"":25} active {"weight":>9} {"hweight%":>13} {"inflt%":>6} ' \
-               f'{"debt":>7} {"delay":>7} {"usage%"}'
+               f'{"usage%":>6} {"wait":>7} {"debt":>7} {"delay":>7}'
 
 class IocgStat:
     def __init__(self, iocg):
@@ -164,6 +164,8 @@ class IocgStat:
 
         self.usage = (100 * iocg.usage_delta_us.value_() /
                       ioc.period_us.value_()) if self.active else 0
+        self.wait_ms = (iocg.stat.wait_us.value_() -
+                        iocg.last_stat.wait_us.value_()) / 1000
         self.debt_ms = iocg.abs_vdebt.value_() / VTIME_PER_USEC / 1000
         if blkg.use_delay.counter.value_() != 0:
             self.delay_ms = blkg.delay_nsec.counter.value_() / 1_000_000
@@ -180,9 +182,10 @@ class IocgStat:
                 'hweight_active_pct'    : self.hwa_pct,
                 'hweight_inuse_pct'     : self.hwi_pct,
                 'inflight_pct'          : self.inflight_pct,
+                'usage_pct'             : self.usage,
+                'wait_ms'               : self.wait_ms,
                 'debt_ms'               : self.debt_ms,
                 'delay_ms'              : self.delay_ms,
-                'usage_pct'             : self.usage,
                 'address'               : self.address }
         return out
 
@@ -192,9 +195,10 @@ class IocgStat:
               f'{round(self.inuse):5}/{round(self.active):5} ' \
               f'{self.hwi_pct:6.2f}/{self.hwa_pct:6.2f} ' \
               f'{self.inflight_pct:6.2f} ' \
+              f'{min(self.usage, 999):6.2f} ' \
+              f'{self.wait_ms:7.2f} ' \
               f'{self.debt_ms:7.2f} ' \
-              f'{self.delay_ms:7.2f} '\
-              f'{min(self.usage, 999):6.2f}'
+              f'{self.delay_ms:7.2f}'
         out = out.rstrip(':')
         return out