[LUNI] SSD drives, part II
Stephan V Bechtolsheim
svbechtolsheim at yahoo.com
Fri Oct 23 11:01:13 CDT 2009
Is it possible to retrieve information about how much time an executable "wasted" in
waiting for I/O to complete?
Let's say at the end of a process I can retrieve the following statistics (the rest of the time
was used by other processes and computations):
- CPU time used: 1.0 Minutes
- Total execution time: 3.0 Minutes
- IO delay and execution time (waiting for IO to complete, etc. etc): 2s
- Number of bytes read: x MB, written: y MB.
This means that if I now had a SSD in the above particular case (very CPU intensive)
the IO time went down from 2s to 0.2s, the overall benefit for this particular application
would be negligible.
I realize that is a crude and simplistic way of looking at it. For instance, if the process
used a database then that time and speedup would not be included in the above
method. But it may be useful anyway as a way of having at least a preliminary estimate
about the speedup.
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