Re: Excessive latency for dev_dbg?

[Joe Perches]

cc'ing Kay.

On Wed, 2012-05-23 at 16:37 -0400, Alan Stern wrote:
> I just tried doing some testing of 3.4.  Sequences of literally
> adjacent dev_dbg() calls -- with local interrupts disabled -- show up
> in the log buffer spaced at time intervals between 1 and 4
> milliseconds!
> 
> This is with CONFIG_DYNAMIC_DEBUG not enabled, and CONFIG_PRINTK_TIME,
> CONFIG_PREEMPT, CONFIG_HIGH_RES_TIMERS, and CONFIG_HPET_TIMER all set
> to y.
> 
> What's going on here?  Did printk suddenly slow down a lot?  Or has the
> timer code gone crazy?


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