*printf(9) and PRINTF_BUFR_SIZE

[Alexander Best]

On Sat Apr  9 11, dieterbsd at engineer.com wrote:
> While working on other problems with *printf(9), log(9), etc.
> I stumbled upon:
> 
> options   PRINTF_BUFR_SIZE=128    # Prevent printf output being 
> interspersed.
> 
> Question 1: Am I correct in thinking that PRINTF_BUFR_SIZE is supposed
> to prevent this:
> 
>   ada2: 300.000MB/s transfuhub2: 3 ports with 3 removable, self powered
>   ers (SATA 2.x, UDMA6, PIO 8192bytes)
>   ada2: Command Queueing enabled
> 
> Question 2: Why is vprintf() the only function that does this buffering?
> As far as I can tell, the various functions that call kvprintf() 
> directly
> without going through vprintf() do not get buffered.  I'm thinking that
> kvprintf() would be a better place for the buffering.  Or would this 
> break
> something?

i remember this issue was discussed a few times before. you might want to
take a look at [1].

cheers.
alex

[1] http://docs.freebsd.org/cgi/mid.cgi?AANLkTinPhcc8Z_BdvoEQUv-ZXlHAYOTQJwlUQDVO8iJ9

> 
> 

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a13x