Re: bugreport: poll() timeout always takes 10ms too long

[raf <raf2@zip.com.au>]

Tachino Nobuhiro wrote:

> 
>  Hello,
> 
> At Fri, 22 Jun 2001 11:52:12 +1000,
> raf@raf.org wrote:
> > 
> > [1.] One line summary of the problem:    
> > 
> > poll() timeout always takes 10ms too long
> > 
> > [2.] Full description of the problem/report:
> > 
> > Select() timeouts work fine. A timeout between 10n-9 and 10n ms times
> > out after 10n ms on average. Poll() timeouts between 10n-9 and 10n ms,
> > on the other hand, time out after 10(n+1) ms on average. It's always a
> > jiffy too long. This means it's impossible to set a 10ms timeout using
> > poll() even though it's possible using select(). The programs and their
> > output below [6] demonstrate this. The same behavious occurs with
> > linux-2.2 and linux-2.4.
> 
> 
>   I think this is correct behavior. The Single UNIX Specification
> describes about the timeout parameter of poll() as follows,
> 
> 	If none of the defined events have occurred on any selected
> 	file descriptor, poll() waits at least timeout milliseconds
> 	for an event to occur on any of the selected file descriptors.
> 
>   On the other hand, select(),
> 
> 	If the specified condition is false for all of the specified
> 	file descriptors, select() blocks, up to the specified timeout
> 	interval, until the specified condition is true for at least
> 	one of the specified file descriptors.

ok, it's a correct behaviour.
but having both poll and select
timeout at the time specified
would also be correct behaviour.
better than that, it would be
expected behaviour.

raf