Re: why kernel implement "udelay" by cpu instructions?

From: Rik van Riel
Date: Wed Nov 04 2009 - 09:17:25 EST

On 11/04/2009 12:36 AM, Bryan Donlan wrote:

I thought hrtimers allow higher-precision wakeups these days?
Of course, if you only want to sleep for a few microseconds, the
context switch might take longer than you want to sleep...

Also, you may not be in a context where you can schedule.

Sometimes drivers need to implement a small delay (to wait
for something on the device) while holding a spinlock or
while interrupts are disabled.

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