:Two things I've noticed:
:1) my cdrom delivers about 2M/s which is the same as before DMA. Is
:the improvement only in cpu usage or should I be seeing a speed
:improvement too?
:
:speed tested with:
:dd if=/dev/racd0c of=/dev/null bs=64k count=320
:(I get it to spin up with another dd before
Matthew Dillon [EMAIL PROTECTED] writes:
:Two things I've noticed:
:1) my cdrom delivers about 2M/s which is the same as before DMA. Is
:the improvement only in cpu usage or should I be seeing a speed
:improvement too?
:
:speed tested with:
:dd if=/dev/racd0c of=/dev/null bs=64k
On 31 Aug 1999, Kevin Street wrote:
Matthew Dillon [EMAIL PROTECTED] writes:
I should have mentioned that ... it's a 32x cdrom. dmesg says it
claims to be able to do 5515 KB/sec.
I've played around with using dd ... skip=n to reposition which part
of the cd I'm reading and I've seen
It seems Kevin Street wrote:
Two things I've noticed:
1) my cdrom delivers about 2M/s which is the same as before DMA. Is
the improvement only in cpu usage or should I be seeing a speed
improvement too?
Depends.. There are many factors involved here, using DMA only lowers
the CPU usage,
Soren Schmidt writes:
Depends.. There are many factors involved here, using DMA only lowers
the CPU usage, and will enable faster transfers if the problem was
that the CPU was saturated with the PIO transfer. It gave about
double the transfer rate on my old P6 based maschine, because the
CPU
David Scheidt [EMAIL PROTECTED] wrote:
Almost all fast (12X or so) CD-ROM drives are variable speed.
To put this a different way, the data on CD's is stored at a constant
lineal density (closely related to the wavelength of the laser).
Audio CDs are read using constant-linear-velocity, the
In message [EMAIL PROTECTED] Kevin Street writes:
: I should have mentioned that ... it's a 32x cdrom. dmesg says it
: claims to be able to do 5515 KB/sec.
Is it a 32x cdrom or a 32x mamimum cdrom? There have been many of the
big-num speed max, smaller-num speed average drives on the market
lineal velocity (and hence data rate) increases from the inside
(start) to the outside (end) of the disk.
And consequently any CD that isn't completely full will *always*
be slower than the quoted ("guaranteed not to exceed") rate.
-- Richard
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On 31-Aug-99 Kevin Street wrote:
Well 2MB/sec == 14x CDRom drive. Is it a 14x CDRom drive? CDRom
drives are typically limited to how quickly they can get data off
the platter. A faster bus transfer will not improve that.
I should have mentioned that ... it's a 32x cdrom.
