After running the vmstat command， which of the following would most likely cause the value in the blocked column to be unusually high？（）

单项选择题Whichofthefollowingcommandsismostusefulininitiallycollectingdatatodetermineanetworkperformanceproblem？（）

A. ping
B. trace
C. ifconfig
D. lsattr

单项选择题To examine the Exhibit， press the Exhibit button. While a user is compiling a C program，  vmstat 120 10  is run to determine the cause of a performance problem.  Given the vmstat output as shown in the exhibit， which of the following conclusions should be drawn about the I O bottleneck？（）

A. There is a file I/O bottleneck.
B. There are too many open files.
C. There appears to be a buffer shortage.
D. There is a paging space I/O bottleneck.

单项选择题WhichofthefollowingmetricsprovidedbytheiostatreportisusedtoinitiallydetermineifasystemisI Obound？（）

A. % idle
B. % sys
C. % user
D. % iowait

单项选择题Whichofthefollowingtoolsshouldbeusedtoreportin-depthinformationaboutfilefragments？（）

A. defragfs
B. istat
C. filemon
D. fileplace

单项选择题Whichofthefollowingperformancetoolscanbeusedtodetermineifasystemisthrashing？（）

A. svmon and tprof
B. vmtune and schedtune
C. ps and schedtune
D. vmstat and topas