Just a quick follow-up on this.
I discovered last night that the reason that switching to 'performance'
made the problem go away is *not* that more CPU power was available, it
was that the CPU frequency no longer changed. My correlation of 'more
CPU usage == music skipping' was in fact basing my diagnosis on a
symptom. In fact, it's more like "more CPU usage == clock speed changes
== music skipping". It occasionally skips still, but it's nowhere near
as bad as it used to be.
So, for now, I've set it to use 'powersave', which is a hack, but a
manageable one.
Other discoveries last night:
- If you disable the fans, the BIOS will turn them on if it really needs
to (but don't blame me if *your* laptop explodes). For some reason,
Ubuntu sets up my computer to always spin the fans slowly rather than
turn them off, so this is preferable for me (it's quieter, and it has
longer battery life).
- Despite DMA being turned on on the hard-disk, there were heaps of
other things that were not. Notably, whilst DMA transfers were enabled,
the drive was programmed to use PIO mode (I actually didn't know that
went as deep as the driver). My laptop is a lot happier with these lines
in my /etc/hdparm.conf file:
/dev/hda {
mult_sect_io = 16
write_cache = off
dma = on
read_ahead_sect = 3072
lookahead = on
io32_support = 1
spindown_time = 6
interrupt_unmask = on
write_cache = on
transfer_mode = 34
}
(again, be careful setting those. The wrong value for transfer_mode will
freeze your computer; it was however, the one that made DMA transfers
worthwhile). The read_ahead value is something I'm experimenting with.
It is my hope that using OS read-ahead will mean that the disk spins
down a bit more.
- Adding 'noatime' to the options in fstab is a 100% awesome thing to do
on a laptop.
- Even though with the new drivers my GPU is quite capable of doing
'Desktop Effects', it makes the GPU chip seriously hot on this machine.
If you're on an older laptop (mine's about 2 years old), this might be a
good thing to do.
HTH someone.
James.
On Thu, 2007-08-02 at 11:04 +1000, James Gregory wrote:
> On Thu, 2007-08-02 at 09:44 +1000, Scott Ragen wrote:
> > James Gregory <[EMAIL PROTECTED]> wrote on 01/08/2007 04:56:26 PM:
> >
> > > So that does substantially help matters -- I have to try pretty hard to
> > > make it skip in that situation. It unfortunately also chews through
> > > battery life and makes the fan scream like some kind of gently blowing
> > > banshee. Needing 1.7GHz of processing power to download email and play
> > > music seems a bit overkill.
> > >
> > > But ok, it may be *switching* performance levels that is the problem
> > > (since that will occur when my mail client wakes up and does stuff). If
> > > that is the case, what kind of things could I do? I've previously tried
> > > re-nicing rhythmbox and esd to -19 and it seemed to have no measurable
> > > effect.
> > >
> > Which driver are you using for the cpufreq?
> > cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_driver
>
> It's set to 'centrino' atm.
>
> > If your using the generic acpi, try the driver specific for your
> > cpu/chipset. If not, try using acpi-cpufreq.
>
> Is this more complicated than echoing the appropriate string into that
> file? I get the following:
>
> # echo "acpi-cpufreq" > /sys/devices/system/cpu/cpu0/cpufreq/scaling_driver
> bash: /sys/devices/system/cpu/cpu0/cpufreq/scaling_driver: Permission denied
>
> And nothing in 'dmesg' telling me what happened.
>
> I did make a little bit of progress on this yesterday. I found that if I
> use the 'conservative' frequency scaler, and renice my various courier
> processes (I use courier-imap for mail) to 19, it's substantially
> better. Still far from flawless, but only a stone's throw from
> tolerable. I might try configuring Evolution to talk directly to the
> Maildir and see what happens.
>
> Thanks for the pointers.
>
> James.
>
> --
> James Gregory -- http://codelore.com -- [EMAIL PROTECTED]
>
>
--
James Gregory -- http://codelore.com -- [EMAIL PROTECTED]
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