Date: Mon, 16 Oct 2006 10:14:02 -0700 From: David King <dking@ketralnis.com> To: freebsd-hardware@freebsd.org Subject: Re: Quiet computer Message-ID: <301DDDB6-A47E-448F-A145-7B2087599598@ketralnis.com> In-Reply-To: <200610140346.22554.soralx@cydem.org> References: <78ED28FACE63744386D68D8A9D1CF5D4209C94@MAIL.corp.lumeta.com> <200610140346.22554.soralx@cydem.org>
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> BTW, David, test (if you have enough time for curiosity) /dev/
> urandom (or
> wherever the generator is) with different values of 'bs', from very
> small to large (1 byte, 512, 4k, 16k, 64k) to see how much it depends
> on block size.
>
>> bash-2.05b$ time dd if=/dev/urandom bs=1024 count=10240 of=/dev/null
>> 10240+0 records in
>> 10240+0 records out
>> 10485760 bytes transferred in 0.154649 secs (67803598 bytes/sec)
~% cat test_rand_block.sh
#!/usr/local/bin/bash
for BS in 1 512 $(expr 1024 \* 4) $(expr 1024 \* 16) $(expr 1024 \*
64); do
COUNT=$(expr $(expr 1024 \* 64) / $BS)
BYTES=$(expr $COUNT \* $BS)
echo bs=$BS count=$COUNT bytes=$BYTES
dd if=/dev/random of=/dev/null bs=$BS count=$COUNT
echo ------;
done
~% sh test_rand_block.sh
bs=1 count=65536 bytes=65536
65536+0 records in
65536+0 records out
65536 bytes transferred in 25.599306 secs (2560 bytes/sec)
------
bs=512 count=128 bytes=65536
128+0 records in
128+0 records out
65536 bytes transferred in 0.099902 secs (656003 bytes/sec)
------
bs=4096 count=16 bytes=65536
16+0 records in
16+0 records out
65536 bytes transferred in 0.100660 secs (651062 bytes/sec)
------
bs=16384 count=4 bytes=65536
4+0 records in
4+0 records out
65536 bytes transferred in 0.099324 secs (659820 bytes/sec)
------
bs=65536 count=1 bytes=65536
1+0 records in
1+0 records out
65536 bytes transferred in 0.099681 secs (657458 bytes/sec)
------
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