sslug-teknik team mailing list archive

[Mogens Kjaer <mk@xxxxxx>]

Kristian Kallenberg wrote:
...
> spock ~ # time dd if=/dev/hda of=/dev/null bs=8192 count=100000
> 100000+0 records in
> 100000+0 records out
> 819200000 bytes (819 MB) copied, 14,4089 s, 56,9 MB/s
>
> real    0m14.413s
> user    0m0.026s
> sys     0m1.223s
>
> spock ~ # time dd if=/dev/hda of=/dev/null bs=8192 count=100000
> 100000+0 records in
> 100000+0 records out
> 819200000 bytes (819 MB) copied, 14,394 s, 56,9 MB/s

Det får jeg ikke:

# time dd if=/dev/sda of=/dev/null bs=8192 count=100000
100000+0 records in
100000+0 records out
819200000 bytes (819 MB) copied, 3.70776 seconds, 221 MB/s

real    0m3.811s
user    0m0.041s
sys     0m0.800s
# time dd if=/dev/sda of=/dev/null bs=8192 count=100000
100000+0 records in
100000+0 records out
819200000 bytes (819 MB) copied, 0.395932 seconds, 2.1 GB/s

Måske er 1G RAM ikke nok til at cache 819MB?

Min maskine har 12G og noget HW RAID-6 halløj :-)

Mogens
--
Mogens Kjaer, Carlsberg A/S, Computer Department
Gamle Carlsberg Vej 10, DK-2500 Valby, Denmark
Phone: +45 33 27 53 25, Fax: +45 33 27 47 08
Email: mk@xxxxxx Homepage: http://www.crc.dk