Re: [bisected] pty performance problem

[Arjan van de Ven]

On Sun, 22 Nov 2009 07:39:26 +0100
Ingo Molnar <mingo@xxxxxxx> wrote:
> > ! Neither has any I/O apart from the pty conversation, so I'd
> > expect to ! see CPU usage at 100%. When I ran it, the CPU was
> > pretty well idle. ! After a fair bit of fiddling, it turned out
> > that both sides were ! taking about 8ms for their read() calls. At
> > that point it seemed ! pretty clear that this was a delay in the
> > kernel, not the code. ! 
> > [snip]
> > 
> > I can provide reasonably stripped down code which demonstrates the
> > problem.  It has been reproduced by one other person, though his
> > delay was about 2ms.


let me guess; you have HZ=250 and the other person has HZ=1000...
since this seems consistent with doing a 1 jiffy delay...


-- 
Arjan van de Ven 	Intel Open Source Technology Centre
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