On 03/07/07 23:13, Fluffles wrote:
Ivan Voras wrote:
Fluffles wrote:
If you use dd on the raw device (meaning no UFS/VFS) there is no
read-ahead. This means that the following DD-command will give lower STR
read than the second:
no read-ahead:
dd if=/dev/mirror/data of=/dev/null bs=1m count=1000
read-ahead and multiple I/O queue depth:
dd if=/mounted/mirror/volume of=/dev/null bs=1m count=1000
I'd agree in theory, but bonnie++ gives WORSE results than raw device:
On what hardware is this? Using any form of geom software RAID?
The low Per Char results would lead me to believe it's a very slow CPU;
maybe VIA C3 or some old pentium? Modern systems should get 100MB/s+ in
per-char bonnie benchmark, even a Sempron 2600+ 1.6GHz 128KB cache which
costs about $39. Then it might be logical DD gets higher results since
this is more 'easy' to handle by the CPU. The VFS/UFS layer adds
potential for nice performance-increases but it does take it's toll in
the form of cputime overhead. If your CPU is very slow, i can imagine
these optimizations having a detrimental effect instead. Just guessing here.
Before making speculative claims about slow CPU's and putting the VIA C3
in with that pile, please at least refer to what makes you believe that
it is an issue. Comparing the VIA C3 to 'some old pentium' isn't
exactly fair or accurate, and inferring it isn't a modern system isn't
true either.
Forgive me though, I'm biased.
Eric
_______________________________________________
freebsd-stable@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-stable
To unsubscribe, send any mail to "[EMAIL PROTECTED]"
