lkml.org 
[lkml]   [2005]   [Jun]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH 3/4] new timeofday x86-64 arch specific changes (v. B1)
Date
On Thursday 02 June 2005 19:20, john stultz wrote:
> Could you see if the slowness you're feeling is correlated to the
> acpi_pm timesource?

Speaking of which, the below code from arch/i386/timer_pm.c looks particularly
more taxing to me - 3 times read from ioport in a loop - not sure how many
time that executes.

static inline u32 read_pmtmr(void)
{
u32 v1=0,v2=0,v3=0;
/* It has been reported that because of various broken
* chipsets (ICH4, PIIX4 and PIIX4E) where the ACPI PM time
* source is not latched, so you must read it multiple
* times to insure a safe value is read.
*/
do {
v1 = inl(pmtmr_ioport);
v2 = inl(pmtmr_ioport);
v3 = inl(pmtmr_ioport);
} while ((v1 > v2 && v1 < v3) || (v2 > v3 && v2 < v1)
|| (v3 > v1 && v3 < v2));
Shouldn't that loop be limited to the broken chipsets - why would correct
people with correctly working chipsets carry this extra burden? (Or is it
insignificant?)

--
Because we don't think about future generations, they will never forget us.
-- Henrik Tikkanen
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-06-03 01:59    [from the cache]
©2003-2011 Jasper Spaans