Le 13/05/2013 17:01, Gandalf Corvotempesta a écrit :
2013/5/13 Greg <itooo@xxxxxxxxx>:
thanks a lot for pointing this out, it indeed makes a *huge* difference !
# dd if=/mnt/t/1 of=/dev/zero bs=4M count=100
100+0 records in
100+0 records out
419430400 bytes (419 MB) copied, 5.12768 s, 81.8 MB/s
(caches dropped before each test of course)
What if you set 1024 or greater value ?
Is bandwidth relative to the read ahead size?
Setting the value too high degrades performance, especially random IO
performance.
You have to determine the right choice for your usage.
Cheers,
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