Messages in this thread | | | Date | Sat, 21 Nov 2009 23:15:14 -0800 | From | Arjan van de Ven <> | Subject | Re: [bisected] pty performance problem |
| |
On Sun, 22 Nov 2009 07:39:26 +0100 Ingo Molnar <mingo@elte.hu> 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 For development, discussion and tips for power savings, visit http://www.lesswatts.org
| |