Re: apm vs. acpi

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On Wed, 2004-12-29 at 08:48 -1000, Amy M wrote:
> All things considered, this fedora-list has become perhaps one of the 
> best forums to learn Linux.  Our sincere thanks to those who are 
> gracious enough to donate their time answering questions that sometimes 
> may seem ridiculous.
> 
> My question now is: From what I have read, it appears that if I want to 
> do suspend to ram, I have to forgo acpi and use apm.  Performance-wise, 
> would anyone care to comment on the pros and cons of acpi vis-a-vis 
> apm?  Thanks again.

Hi Amy,

I can only relate my FC kernel-2.6 experiences for one laptop, a
ThinkPad A22p (PIII-900) and they are:

 - with very recent kernels (eg. 2.6.9-1.681_FC3) both APM 
   and ACPI suspend-to-RAM work
 - with both I often need to unload and then re-load the 
   sound kernel modules
 - APM:
   - uses *very* little power when suspended to RAM (lasts 
     for many days starting from a full charge)
   - can occasionally have problems with pcmcia (even when
     all cards are removed) so I usually use:  
       "/etc/init.d/pcmcia stop ; apm -s"
     and then restart pcmcia after wake-up with:
       "/etc/init.d/pcmcia start"
   - results in lockups about once every 40--50 suspend-
     resume cycles
 - ACPI:
   - has no apparent problems with pcmcia
   - experienced no lockups (in about ~60 cycles)
   - uses a *LOT* (perhaps as much as 10X) more battery 
     power while suspended to RAM
   - suspends and resumes very quickly
   - routinely gives a kernel error on wakeup saying 
     something about interruptable_sleep() but they seem 
     to be harmless

Having done many hundreds of suspend-resume cycles using both APM and
ACPI, I've decided to stick with APM to reduce the battery usage.

Ed

-- 
Edward H. Hill III, PhD
office:  MIT Dept. of EAPS;  Rm 54-1424;  77 Massachusetts Ave.
             Cambridge, MA 02139-4307
emails:  eh3@xxxxxxx                ed@xxxxxxx
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