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From: Roger Larsson <roger.larsson@norran.net>
To: Andre Hedrick <andre@linux-ide.org>, schwidefsky@de.ibm.com,
        george anzinger <george@mvista.com>
Subject: Re: Linux-Kernel Archive: No 100 HZ timer !
Date: Sun, 15 Apr 2001 04:10:34 +0200
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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
Skellefte?
Sweden
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