- How much RAM do you have? What did the Task Manager (Windows) free ram show during execution.
- Did anything I/O-intensive run simultaneously?
Textscan and cpu usage
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I used textscan to read a csv file of 0.5 GB. Sometimes it took less than a minute to complete but in another time it took almost 10 minutes! When I compare the cpu usages during those instances, I noticed that the cpu usage is high for the former (25% in a quadcores machine, so a full core) and low for the latter (less than 5%). Anybody has this experience?
3 Commenti
per isakson
il 7 Ott 2017
- This large difference in speed makes me think about swapping, but that isn't likely with 8GB RAM. Did try to use the Resource Manager to see what's going on?
- I once tested speed of I/O with some large files. I had problems to reproduce the results. End of story: I drew the conclusion that my test "messed up" the system cache, which in turn increased the execution times, but certainly not an order of magnitude.
- I often use fileread in combination with textscan, when the string needs some fixing before parsing. I was initially surprised it is nearly as fast as reading with textscan.
- Which versions of Matlab and Windows do you use?
Risposte (1)
Kian Azami
il 7 Ott 2017
Modificato: per isakson
il 7 Ott 2017
I just heard that the computation process by the cpu is a very nonlinear process and for this reason every time you see a different behavior. There are some publication about this issue, to study the behavior of the cpu computations.
I put a youtube link which one of the prominent scientists talks about this issue. Worth to listen! https://www.youtube.com/watch?time_continue=17&v=iW2QJRDEBMw
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