Daniel O'Connor wrote in list.freebsd-current:
> 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 impro
On 01-Sep-99 Daniel O'Connor wrote:
> Of course given the advent of CLV drives a speed rating is now usually the
> maximum read speed, not the average.
Oops.. I mean CAV drives..
Constant Angular Velocity not Constant Linear Velocity.
---
Daniel O'Connor software and network engineer
for Gene
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 cd
> 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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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
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 an
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
>CP
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,
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'v
< said:
> All modern CDRom units have vibration sensors (actually I think they
> just use the error rate from the head) and will adjust the rotational
> speed based on that as well as on the rate the data is being requested
> at. So it will depend on the physical CD as well as ot
: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/n
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
: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 t
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 this test)
A little while ago I enabled DMA on atapi devices, and while this
generally is a good thing (CPU usage wise), there seems to be
some delicate problems with this on some chipsets and devices.
If you use the new ATA driver and has atapi devices that use DMA
could you please check that they are wor
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