Messages in this thread | | | From | Hans Henrik Happe <> | Subject | Re: Issues with INET sockets through loopback (lo) | Date | Tue, 24 May 2005 14:12:17 +0200 |
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On Monday 23 May 2005 14:09, DervishD wrote: > With 3-1 I get an usage of 20% more or less. But with 16-1 the > CPU usage is nearly 0! and with 16-16 the usage is 5% more or less.
That even worse than what I have experienced.
> > I have tried more regular communication patterns but this gives full CPU > > utilization as expected. For instance sending messages in a ring (attach: > > ring-inet.c). > > Not here. It uses 29% instead of 20% with 3-1, but drops to 6% > when using 16 processes. Far from full CPU usage. A test with 16-160 > doesn't make the system slower or irresponsive, at least here...
Again, even worse.
> Not here. I haven't noticed any slow-down or latency increase > using high number of messages. Using 16-160 only uses at most 7% of > CPU per process, and I don't feel the system irresponsive.
That's strange. Maybe I should try an AMD system myself. Btw the number of processes is an upper bound of the number of messages. This is just a simplification in the code.
> If you want more accurate results, try to modify your test > programs: make them run for a couple of minutes (you decide how much > time, the longer, the better) and kill all children processes. After > that, use getrusage() (with RUSAGE_CHILDREN) or wait3(). That should > give more accurate results.
I could do that, but my point is that kernel goes into the idle state even though there always should be a runable process. Your tests supports this. I don't believe that more accuracy would help because it is quite clear that CPU is in the idle state.
> Hope that helps. If you want to make any other test, tell me. > I'll try to help.
Thanx. Your tests actually confirms the first issue, which also is the one that I have been most concerned about.
I hope that someone with knowledge of how this part of the kernel work can confirm that this is a problem with the kernel or explain why it is supposed to behave in this manor.
Hans Henrik Happe - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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