Re: Linux-Kernel Archive: No 100 HZ timer !

From: Roger Larsson (roger.larsson@norran.net)
Date: Sat Apr 14 2001 - 21:10:34 EST


On Thursday 12 April 2001 23:52, Andre Hedrick wrote:
> Okay but what will be used for a base for hardware that has critical
> timing issues due to the rules of the hardware?
>
> I do not care but your drives/floppy/tapes/cdroms/cdrws do:
>
> /*
> * Timeouts for various operations:
> */
> #define WAIT_DRQ (5*HZ/100) /* 50msec - spec allows up to 20ms
> */ #ifdef CONFIG_APM
> #define WAIT_READY (5*HZ) /* 5sec - some laptops are very
> slow */ #else
> #define WAIT_READY (3*HZ/100) /* 30msec - should be instantaneous
> */ #endif /* CONFIG_APM */
> #define WAIT_PIDENTIFY (10*HZ) /* 10sec - should be less than 3ms (?), if
> all ATAPI CD is closed at boot */ #define WAIT_WORSTCASE (30*HZ) /* 30sec
> - worst case when spinning up */ #define WAIT_CMD (10*HZ) /* 10sec
> - maximum wait for an IRQ to happen */ #define WAIT_MIN_SLEEP (2*HZ/100)
> /* 20msec - minimum sleep time */
>
> Give me something for HZ or a rule for getting a known base so I can have
> your storage work and not corrupt.
>

Wouldn't it make sense to define these in real world units?
And to use that to determine requested accuracy...

Those who wait for seconds will probably not have a problem with up to (half)
a second longer wait - or...?
Those in range of the current jiffie should be able to handle up to one
jiffie longer...

Requesting a wait in ms gives yo ms accuracy...

/RogerL

-- 
Roger Larsson
Skellefteċ
Sweden
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