当我运行以下代码时，循环所有进程需要两分钟。这是正常的吗？我一直在使用psutil.process_iter（）一段时间，我不记得它很久以前就这么做了。
import psutil
import datetime as dt
for proc in psutil.process_iter():
try:
pinfo = proc.as_dict(attrs=['pid', 'name'])
except psutil.NoSuchProcess:
pass
else:
print(pinfo)
print dt.datetime.now()
输出：
{'pid': 0, 'name': 'System Idle Process'}
2017-07-11 01:55:45.392000
{'pid': 4, 'name': 'System'}
2017-07-11 01:55:45.394000
{'pid': 256, 'name': 'acrotray.exe'}
2017-07-11 01:55:45.397000
{'pid': 404, 'name': None}
2017-07-11 01:55:46.670000
{'pid': 568, 'name': None}
2017-07-11 01:55:47.750000
{'pid': 604, 'name': None}
2017-07-11 01:55:48.996000
{'pid': 608, 'name': None}
2017-07-11 01:55:50.293000
{'pid': 700, 'name': None}
2017-07-11 01:55:51.492000
{'pid': 708, 'name': None}
2017-07-11 01:55:52.587000
{'pid': 784, 'name': None}
2017-07-11 01:55:55.319000
{'pid': 836, 'name': None}
2017-07-11 01:55:56.537000
{'pid': 844, 'name': None}
2017-07-11 01:55:57.898000
{'pid': 948, 'name': None}
2017-07-11 01:55:59.103000
{'pid': 1012, 'name': None}
2017-07-11 01:56:00.267000
{'pid': 1036, 'name': None}
2017-07-11 01:56:02.072000
{'pid': 1112, 'name': None}
2017-07-11 01:56:04.072000
{'pid': 1120, 'name': None}
2017-07-11 01:56:05.266000
{'pid': 1176, 'name': None}
2017-07-11 01:56:06.476000
{'pid': 1292, 'name': None}
2017-07-11 01:56:08.451000
{'pid': 1352, 'name': None}
2017-07-11 01:56:09.660000
{'pid': 1432, 'name': None}
2017-07-11 01:56:10.915000
{'pid': 1456, 'name': None}
2017-07-11 01:56:12.206000
{'pid': 1480, 'name': 'svchost.exe'}
2017-07-11 01:56:12.208000
{'pid': 1516, 'name': None}
2017-07-11 01:56:13.293000
{'pid': 1576, 'name': None}
2017-07-11 01:56:14.525000
{'pid': 1640, 'name': None}
2017-07-11 01:56:15.831000
{'pid': 1660, 'name': None}
2017-07-11 01:56:17.055000
{'pid': 1728, 'name': None}
2017-07-11 01:56:19.045000
{'pid': 1992, 'name': 'RAVBg64.exe'}
2017-07-11 01:56:19.047000
{'pid': 2084, 'name': None}
2017-07-11 01:56:20.311000
{'pid': 2140, 'name': None}
2017-07-11 01:56:21.391000
{'pid': 2192, 'name': 'googledrivesync.exe'}
2017-07-11 01:56:21.393000
{'pid': 2220, 'name': None}
2017-07-11 01:56:22.756000
{'pid': 2340, 'name': None}
2017-07-11 01:56:23.984000
{'pid': 2552, 'name': None}
2017-07-11 01:56:25.180000
{'pid': 2612, 'name': None}
2017-07-11 01:56:27.439000
{'pid': 2660, 'name': None}
2017-07-11 01:56:29.048000
{'pid': 2676, 'name': None}
2017-07-11 01:56:30.170000
{'pid': 2700, 'name': None}
2017-07-11 01:56:31.481000
{'pid': 2720, 'name': None}
2017-07-11 01:56:32.927000
{'pid': 2760, 'name': None}
2017-07-11 01:56:34.823000
{'pid': 2844, 'name': None}
2017-07-11 01:56:37.056000
{'pid': 2872, 'name': None}
2017-07-11 01:56:38.139000
{'pid': 2880, 'name': None}
2017-07-11 01:56:39.580000
{'pid': 2912, 'name': None}
2017-07-11 01:56:40.814000
{'pid': 2976, 'name': 'taskhostw.exe'}
2017-07-11 01:56:40.815000
{'pid': 3408, 'name': 'sihost.exe'}
2017-07-11 01:56:40.817000
{'pid': 3436, 'name': None}
2017-07-11 01:56:42.011000
{'pid': 3788, 'name': None}
2017-07-11 01:56:44.004000
{'pid': 3824, 'name': None}
2017-07-11 01:56:45.243000
{'pid': 4160, 'name': None}
2017-07-11 01:56:46.458000
{'pid': 4308, 'name': None}
2017-07-11 01:56:49.129000
{'pid': 4536, 'name': None}
2017-07-11 01:56:50.274000
{'pid': 4788, 'name': 'dllhost.exe'}
2017-07-11 01:56:50.276000
{'pid': 5136, 'name': None}
2017-07-11 01:56:51.445000
{'pid': 5264, 'name': None}
2017-07-11 01:56:52.771000
{'pid': 5284, 'name': None}
2017-07-11 01:56:54.653000
{'pid': 5408, 'name': None}
2017-07-11 01:56:56.155000
{'pid': 5492, 'name': None}
2017-07-11 01:56:57.365000
{'pid': 5508, 'name': 'AnyDesk.exe'}
2017-07-11 01:56:57.366000
{'pid': 5660, 'name': None}
2017-07-11 01:56:58.456000
{'pid': 5764, 'name': 'svchost.exe'}
2017-07-11 01:57:00.759000
{'pid': 5936, 'name': 'RuntimeBroker.exe'}
2017-07-11 01:57:00.761000
{'pid': 5948, 'name': None}
2017-07-11 01:57:02.096000
{'pid': 5964, 'name': 'explorer.exe'}
2017-07-11 01:57:02.098000
{'pid': 6124, 'name': None}
2017-07-11 01:57:04.011000
{'pid': 6160, 'name': 'googledrivesync.exe'}
2017-07-11 01:57:04.013000
{'pid': 6348, 'name': None}
2017-07-11 01:57:05.390000
{'pid': 6400, 'name': None}
2017-07-11 01:57:06.715000
{'pid': 6476, 'name': None}
2017-07-11 01:57:07.927000
{'pid': 6544, 'name': None}
2017-07-11 01:57:09.148000
{'pid': 6556, 'name': 'jusched.exe'}
2017-07-11 01:57:09.150000
{'pid': 6600, 'name': None}
2017-07-11 01:57:10.441000
{'pid': 6856, 'name': None}
2017-07-11 01:57:11.516000
{'pid': 6916, 'name': None}
2017-07-11 01:57:12.739000
{'pid': 7040, 'name': 'AnyDesk.exe'}
2017-07-11 01:57:14.822000
{'pid': 7052, 'name': None}
2017-07-11 01:57:16.707000
{'pid': 7112, 'name': None}
2017-07-11 01:57:18.072000
{'pid': 7328, 'name': 'HD-Agent.exe'}
2017-07-11 01:57:18.074000
{'pid': 7860, 'name': 'ShellExperienceHost.exe'}
2017-07-11 01:57:18.076000
{'pid': 8048, 'name': 'SearchUI.exe'}
2017-07-11 01:57:18.078000
{'pid': 8240, 'name': None}
2017-07-11 01:57:19.279000
{'pid': 8444, 'name': 'RtkNGUI64.exe'}
2017-07-11 01:57:19.281000
{'pid': 8492, 'name': 'python.exe'}
2017-07-11 01:57:19.282000
{'pid': 8628, 'name': 'MSASCuiL.exe'}
2017-07-11 01:57:19.284000
{'pid': 9000, 'name': None}
2017-07-11 01:57:20.370000
{'pid': 9012, 'name': 'nvtray.exe'}
2017-07-11 01:57:20.372000
{'pid': 9132, 'name': None}
2017-07-11 01:57:21.634000
{'pid': 9188, 'name': 'NvBackend.exe'}
2017-07-11 01:57:21.636000
{'pid': 11876, 'name': 'mmc.exe'}
2017-07-11 01:57:21.638000
{'pid': 340664, 'name': None}
2017-07-11 01:57:24.284000
{'pid': 1341072, 'name': 'OneDrive.exe'}
2017-07-11 01:57:24.285000
{'pid': 2065140, 'name': 'taskhostw.exe'}
2017-07-11 01:57:24.287000
{'pid': 2091584, 'name': None}
2017-07-11 01:57:25.505000
{'pid': 2676980, 'name': None}
2017-07-11 01:57:26.867000
{'pid': 2684020, 'name': None}
2017-07-11 01:57:28.049000
{'pid': 2684616, 'name': None}
2017-07-11 01:57:29.613000
{'pid': 2684628, 'name': None}
2017-07-11 01:57:31.347000
{'pid': 3016072, 'name': 'SkypeHost.exe'}
2017-07-11 01:57:31.348000
{'pid': 4308396, 'name': 'splwow64.exe'}
2017-07-11 01:57:31.350000
{'pid': 4510700, 'name': None}
2017-07-11 01:57:32.848000
{'pid': 4925868, 'name': None}
2017-07-11 01:57:34.734000
{'pid': 4964188, 'name': 'TvUpdateInfo.exe'}
2017-07-11 01:57:34.736000
{'pid': 4966736, 'name': None}
2017-07-11 01:57:36.912000
{'pid': 4967852, 'name': None}
2017-07-11 01:57:37.995000
{'pid': 5006116, 'name': 'TeamViewer.exe'}
2017-07-11 01:57:37.997000
{'pid': 5016052, 'name': None}
2017-07-11 01:57:39.229000
{'pid': 5021384, 'name': None}
2017-07-11 01:57:40.531000
{'pid': 5021508, 'name': None}
2017-07-11 01:57:41.750000
{'pid': 5022036, 'name': None}
2017-07-11 01:57:43.765000
{'pid': 5022176, 'name': None}
2017-07-11 01:57:45.023000
{'pid': 5258664, 'name': 'chrome.exe'}
2017-07-11 01:57:45.024000
{'pid': 5469448, 'name': 'chrome.exe'}
2017-07-11 01:57:45.026000
{'pid': 5479292, 'name': 'chrome.exe'}
2017-07-11 01:57:45.028000
{'pid': 5500760, 'name': 'chrome.exe'}
2017-07-11 01:57:45.029000
{'pid': 5539972, 'name': 'chrome.exe'}
2017-07-11 01:57:45.031000
{'pid': 5540664, 'name': 'chrome.exe'}
2017-07-11 01:57:45.035000
{'pid': 5546088, 'name': 'chrome.exe'}
2017-07-11 01:57:45.044000
{'pid': 5561092, 'name': 'chrome.exe'}
2017-07-11 01:57:45.048000
{'pid': 5561948, 'name': 'chrome.exe'}
2017-07-11 01:57:45.049000
{'pid': 5562356, 'name': 'chrome.exe'}
2017-07-11 01:57:45.055000
{'pid': 6958780, 'name': 'bxlaui.exe'}
2017-07-11 01:57:45.065000
{'pid': 7234036, 'name': 'bplus.exe'}
2017-07-11 01:57:45.071000
{'pid': 7261260, 'name': 'InstallAgent.exe'}
2017-07-11 01:57:45.080000
{'pid': 7261348, 'name': 'InstallAgentUserBroker.exe'}
2017-07-11 01:57:45.085000
{'pid': 7488312, 'name': 'bplus.exe'}
2017-07-11 01:57:45.089000
{'pid': 7755192, 'name': 'WINTRV.EXE'}
2017-07-11 01:57:45.100000
{'pid': 7758992, 'name': 'blpaddinhost.exe'}
2017-07-11 01:57:45.106000
{'pid': 7767328, 'name': 'chrome.exe'}
2017-07-11 01:57:45.115000
{'pid': 7790252, 'name': 'blpcbbap.exe'}
2017-07-11 01:57:45.119000
{'pid': 7801644, 'name': 'bxlartd.exe'}
2017-07-11 01:57:45.121000
{'pid': 7804804, 'name': 'bplus.exe'}
2017-07-11 01:57:45.125000
{'pid': 7804824, 'name': None}
2017-07-11 01:57:46.232000
{'pid': 7806284, 'name': 'bbcomm.exe'}
2017-07-11 01:57:46.233000
{'pid': 7806924, 'name': 'wui2manager.exe'}
2017-07-11 01:57:46.235000
{'pid': 7821280, 'name': None}
2017-07-11 01:57:49.104000
{'pid': 7844804, 'name': 'python.exe'}
2017-07-11 01:57:49.105000
{'pid': 7851064, 'name': 'python.exe'}
2017-07-11 01:57:49.107000
{'pid': 7854772, 'name': 'blpsmarthost.exe'}
2017-07-11 01:57:49.109000
{'pid': 7854856, 'name': 'ipython.exe'}
2017-07-11 01:57:49.111000
{'pid': 7855228, 'name': None}
2017-07-11 01:57:50.187000
{'pid': 7857920, 'name': 'cmd.exe'}
2017-07-11 01:57:50.189000
{'pid': 7858064, 'name': 'conhost.exe'}
2017-07-11 01:57:50.191000
{'pid': 7858352, 'name': 'bplus.exe'}
2017-07-11 01:57:50.193000
{'pid': 7858368, 'name': 'bplus.exe'}
2017-07-11 01:57:50.194000
{'pid': 7858372, 'name': None}
2017-07-11 01:57:51.523000
{'pid': 7872880, 'name': 'conhost.exe'}
2017-07-11 01:57:51.526000
{'pid': 7874176, 'name': 'ipython.exe'}
2017-07-11 01:57:51.534000
{'pid': 7874248, 'name': 'cmd.exe'}
2017-07-11 01:57:51.538000
{'pid': 7874272, 'name': 'conhost.exe'}
2017-07-11 01:57:51.540000
{'pid': 7874328, 'name': 'python.exe'}
2017-07-11 01:57:51.544000
{'pid': 7876140, 'name': 'chrome.exe'}
2017-07-11 01:57:51.554000
{'pid': 7879120, 'name': 'smartscreen.exe'}
2017-07-11 01:57:51.560000
{'pid': 7879584, 'name': 'cmd.exe'}
2017-07-11 01:57:51.569000
{'pid': 7879592, 'name': 'conhost.exe'}
2017-07-11 01:57:51.573000