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SubjectRe: [PATCH 3/4] new timeofday x86-64 arch specific changes (v. B1)
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

Because we don't think about future generations, they will never forget us.
-- Henrik Tikkanen
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