如何解释perf iTLB负载,iTLB-load-miss

Question

我有一个测试用例来观察iTLB负载,iTLB负载未命中

perf stat -e dTLB-loads,dTLB-load-misses,iTLB-loads,iTLB-load-misses -p 22479

并得到输出:

进程ID"22479"的性能计数器统计信息:

     1,262,817      dTLB-loads                                                  
        13,950      dTLB-load-misses          #    1.10% of all dTLB cache hits 
            75      iTLB-loads                                                  
         6,882      iTLB-load-misses          # 9176.00% of all iTLB cache hits 

   3.999720948 seconds time elapsed

我不知道如何解释iTLB负载仅75但iTLB负载未命中6,882？

lscpu showes:Intel(R)Xeon(R)CPU E5-2620 v4 @ 2.10GHz

编辑:

我可以解释如下:

做(75 + 6882)次iTLB负载,有75次点击但6882次未命中？

编辑:

ocperf.py list | wc -l
Downloading https://download.01.org/perfmon/mapfile.csv to mapfile.csv

Traceback (most recent call last):
File "/home/marschen/tools/pmu-tools-master/ocperf.py", line 1012, in <module>
emap = find_emap()
File "/home/marschen/tools/pmu-tools-master/ocperf.py", line 831, in find_emap
event_download.download(el, toget)
File "/home/marschen/tools/pmu-tools-master/event_download.py", line 105, in download
getfile(modelpath, dir, "mapfile.csv")
File "/home/marschen/tools/pmu-tools-master/event_download.py", line 86, in getfile
f = urlopen(url)
File "/usr/lib64/python2.7/urllib2.py", line 154, in urlopen
return opener.open(url, data, timeout)
File "/usr/lib64/python2.7/urllib2.py", line 431, in open
response = self._open(req, data)
File "/usr/lib64/python2.7/urllib2.py", line 449, in _open
'_open', req)
File "/usr/lib64/python2.7/urllib2.py", line 409, in _call_chain
result = func(*args)
File "/usr/lib64/python2.7/urllib2.py", line 1258, in https_open
context=self._context, check_hostname=self._check_hostname)
File "/usr/lib64/python2.7/urllib2.py", line 1211, in do_open
h.request(req.get_method(), req.get_selector(), req.data, headers)
File "/usr/lib64/python2.7/httplib.py", line 1017, in request
self._send_request(method, url, body, headers)
File "/usr/lib64/python2.7/httplib.py", line 1051, in _send_request
self.endheaders(body)
File "/usr/lib64/python2.7/httplib.py", line 1013, in endheaders
self._send_output(message_body)
File "/usr/lib64/python2.7/httplib.py", line 864, in _send_output
self.send(msg)
File "/usr/lib64/python2.7/httplib.py", line 826, in send
self.connect()
File "/usr/lib64/python2.7/httplib.py", line 1227, in connect
HTTPConnection.connect(self)
File "/usr/lib64/python2.7/httplib.py", line 807, in connect
self.timeout, self.source_address)
File "/usr/lib64/python2.7/socket.py", line 562, in create_connection
sock.connect(sa)
File "/usr/lib64/python2.7/socket.py", line 224, in meth
return getattr(self._sock,name)(*args)

Answer 1

在您的Broadwell微架构处理器,香水,映射iTLB-loads到ITLB_MISSES.STLB_HIT,它代表了TLB查找的是错过了L1 ITLB但命中统一TLB所有页面大小,和事件iTLB-load-misses来ITLB_MISSES.MISS_CAUSES_A_WALK,这代表了TLB查找未命中两个L1 ITLB和事件所有页面大小的统一TLB(导致页面遍历).因此,iTLB-load-misses可以大于或小于等于iTLB-loads.他们是独立的事件.