Re: [Syllable-kernel] Arno's kernel patches

[Jake H. <jh...@po...>]

Arno Klenke wrote:
> The kernel patch is now available. It changes the following things:
> 
> *Fixes the acpi table parsing errors and adds a kernel option to disable 
> the acpi support
> *Removes the unnecessary cli()/put_cpu_flags() calls
> *Removes the reflect_irq_to_realmode() call

Sounds good.  I'll check them in soon.

> P.S.: Your code to increase the timer precision has caused a really 
> _huge_ performance drop on my system

Interesting.  There must be something in the kernel or in user space 
that is calling get_system_time() or get_real_time() frequently enough 
for the overhead of disabling interrupts and reading the PIT timer value 
to be noticable.  I'll look into it.

Speaking of bad performance, I'm frustrated that there are a couple of 
threads that chew up a big chunk of CPU time on my system:

dbterm:  main thread (14%), read thread (7%)
media_server_flush:  21.7%
ata_cmd_thread:  up to 17% for each thread
appserver: keyb_thread: 7.1%
appserver: input_thread:  2.6%

I haven't yet been able to look into why these threads are using so much 
CPU time, but, except for the ata_cmd_threads, the problems seem to be 
due to polling and snoozing for events rather than blocking until an 
event arrives.

-Jake