[linux-audio-user] APIC is bad? What about hdparm?

tim hall tech at glastonburymusic.org.uk
Sat Jul 17 13:12:39 EDT 2004

Last Saturday 17 July 2004 12:53, Malcolm Baldridge was like:
> If you're "on the borderline" with xruns, you might gain something by
> tuning your IDE driver with a smaller or larger -m setting.  Try -m1, -m4,
> -m8, or -m16.

One of my harddrives actually seems to prefer -m32

> Finally, this may sound weird and voodoo, but make sure your IDE cables
> aren't too twisted or molested.  Cable CRC errors do happen and they cause
> abrupt transfer speed aberrations.

No, I've heard it enough times. Actually, this may well be worth me checking. 
I have one of those stupidly small cases, it's pretty hard not to twist the 
IDE cables a bit. I know, I am a compulsive cable straightener / untangler - 
intuitively, tangled cables carrying electrical signals has never seemed like 
a good idea.

> If you install smartmontools (S.M.A.R.T. drive logging/diagnostic tool),
> you can inquire of cabling CRC errors and note whether or not you seem to
> be getting alot of them in your system.
> I have yet to meet a post-440FX (Pentium era) chipset whose Linux IDE
> driver 'sperformance was not radically improved with a massive reduction in
> CPU utilisation during heavy disk I/O when the IDE driver was tuned with
> -c1 -u1 -d1 versus one which was NOT tuned.  -c1 may not provide any
> tangible benefit, but -d1 definitely does, and -u1 gets you released from
> IRQ-hold-off states within the driver a bit earlier.  Modern kernels built
> with specific IDE chipset support are doing a better job of configuring
> these with good defaults.  Verify it with: hdparm -v /dev/hda

-u1 has the most tangible benefit, I don't know if that really applies to 
music, but it does mean that the system can do something else at the same 
time as redrawing the screen, which does give an immediately noticeable 

The AGNULA system that I use now comes with these hdparm settings as default, 
so I probably don't need to look at that again.

Last Saturday 17 July 2004 14:58, RickTaylor at speakeasy.net was like:
> You do have to be careful with it. You can fry your drive.

Yep, don't try this at home, kids. At least back well up and RTFM first. I did 
it gently and then backed off at the first signs of disk misreads. Me not 
silly ;-)


tim hall

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