Messages in this thread | | | Date | Wed, 24 Aug 2005 10:26:31 -0700 (PDT) | From | Danial Thom <> | Subject | Re: 2.6.12 Performance problems |
| |
--- Jesper Juhl <jesper.juhl@gmail.com> wrote:
> On 8/24/05, Danial Thom <danial_thom@yahoo.com> > wrote: > > --- Patrick McHardy <kaber@trash.net> wrote: > > > > > Danial Thom wrote: > > > > I think part of the problem is the > continued > > > > misuse of the word "latency". Latency, in > > > > language terms, means "unexplained > delay". > > > Its > > > > wrong here because for one, its > explainable. > > > But > > > > it also depends on your perspective. The > > > > "latency" is increased for kernel tasks, > > > while it > > > > may be reduced for something that is > getting > > > the > > > > benefit of preempting the kernel. So you > > > really > > > > can't say "the price of reduced latency > is > > > lower > > > > throughput", because thats simply > backwards. > > > > You've increased the kernel tasks latency > by > > > > allowing it to be pre-empted. Reduced > latency > > > > implies higher efficiency. All you've > done > > > here > > > > is shift the latency from one task to > > > another, so > > > > there is no reduction overall, in fact > there > > > is > > > > probably a marginal increase due to the > > > overhead > > > > of pre-emption vs doing nothing. > > > > > > If instead of complaining you would provide > the > > > information > > > I've asked for two days ago someone might > > > actually be able > > > to help you. > > > > Because gaining an understanding of how the > > settings work is better than having 30 guys > > telling me to tune something that is only > going > > to make a marginal difference. I didn't ask > you > > to tell me what was wrong with my setup, only > > whether its expected that 2.6 would be less > > useful in a UP setup than 2.4, which I think > > you've answered. > > > > I hope you're implying that the answer is; no, > it's not expected that > 2.6 is less useful in a UP setup than 2.4 :-)
I think the concensus is that 2.6 has made trade offs that lower raw throughput, which is what a networking device needs. So as a router or network appliance, 2.6 seems less suitable. A raw bridging test on a 2.0Ghz operton system:
FreeBSD 4.9: Drops no packets at 900K pps Linux 2.4.24: Starts dropping packets at 350K pps Linux 2.6.12: Starts dropping packets at 100K pps
Now the 2.6.12 keyboard is always nice and snappy, but thats not what I need. I can't have a box drop traffic if some admin decides to recompile some application. Linux is fine on low-medium speed networks, but at a certain capacity, depending on the specs of the machine of course, linux drops packets.
If I do a "make install" in BSD when on a busy network, it takes a long time, but it doesn't drop packets. Linux compiles a lot faster, but it drops buckets of packets. Its just not the priority thats needed for a networking device.
Danial
____________________________________________________ Start your day with Yahoo! - make it your home page http://www.yahoo.com/r/hs - 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/
| |