Messages in this thread | | | Date | Wed, 17 Mar 1999 02:13:39 +0100 (CET) | From | Andrea Arcangeli <> | Subject | Re: [patch] recover losed timer interrupt using the TSC [Re: [patch] kstat change to see how much Linux SMP really scale well] |
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On Tue, 16 Mar 1999, Ulrich Windl wrote:
>[...] > >> + register unsigned long delta_usec; >> + >> + __asm__("mull %2" >> + :"=a" (delta_cycles), "=d" (delta_usec) >> + :"g" (fast_gettimeoffset_quotient), "0" (delta_cycles)); >> + delta_usec -= delay_usec; >> + delta_usec /= 1000000/HZ; > >Your delta_usec is in fact a lost_ticks. The name is confusing when >you add microseconds to jiffies. (IMHO)
Ok, agreed. It was not a problem right now but removing the `_usec' could be a better choice. Thanks.
>> -long tick = (1000000 + HZ/2) / HZ; /* timer interrupt period */ >> +long tick = 1000000 / HZ; /* timer interrupt period */ > >This way the system time will be more behind than before if >"(1000000 % HZ) >= HZ/2". IMHO the line is correct. After all we are >not saying "(1000000 + HZ - 1) / HZ".
;). Agreed. I also needed such trick that to make the recover of the lost ticks completly relialable. I just removed such changes from my second patch. But thanks for commenting about that. I wanted to hear if I was missing something of more serious or it was only an attempt to decrease the error in integer divisions.
Andrea Arcangeli
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