Fix to avoid premature exit#1
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Hi Thanks for the pull request! This is not about how fast is disc access etc... and I'm not flushing to disk in any example. So I guess comparison is fare enough. What do you think ? Thanks, |
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Hi! If you don't sync after the (zero copy) sendfile call the disk write gets queued (on my linux system) and you can't compare the execution time! Regards |
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Hi!
You should sync with the destination to avoid wrong measurement results.
No sync:
./fcopy /tmp/rbigfile.dat /tmp/wbigfile2.dat 2 0.00s user 0.24s system 99% cpu 0.242 total
0.242 seconds for a 1 GB file on a ~180MB/s hard disk...
grep Dirty /proc/meminfo
Dirty: 1048476 kB
There we go, dirty memory that isn't flushed yet to the disk!
After adding the fdatasync call:
./fcopy /tmp/rbigfile.dat /tmp/wbigfile2.dat 2 0.00s user 0.32s system 4% cpu 6.461 total
Regards!