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

[Parag Warudkar <kernel-stuff@comcast.net>]

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