input

I/O multiplexing: select, poll and epoll in Linux

1.0 I/O multiplexing

I/O multiplexing is the the ability to perform I/O operations on multiple file descriptors. Input operations like read, accept and calls for receiving messages block when there is no incoming data. So, if an input call is made and it blocks, we may miss data from other file descriptors.… Read more

iostat

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The iostat command is for getting the CPU and input-output devices' statistics for Linux and Unix systems. For example,

$ iostat
Linux 3.0.0-14-generic (hostname) 	Wednesday 06 June 2012 	_i686_	(2 CPU)  

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
          17.38    0.13    3.13    1.63    0.00   77.74

Device:            tps    kB_read/s    kB_wrtn/s    kB_read    kB_wrtn
sda              11.78       111.65        69.79   11663838    7290650

The above output has two reports, the CPU utilization report and the device utilization report.… Read more