Messages in this thread | | | Date | Mon, 03 Oct 2011 12:28:13 -0400 | From | starlight@binnacle ... | Subject | Re: big picture UDP/IP performance question re 2.6.18 -> 2.6.32 |
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At 06:16 PM 10/3/2011 +0200, Eric Dumazet wrote: >> >Please send full "dmesg" output >> >> Attached. >> > >Minor note : > >It seems you use 4096 2MB hugepages, and your >machine has 1GB pages availabe, you could >try to use them. > >(boot cmd : hugepagesz=1GB hugepages=8 )
Interesting. I'll give it a try for sure, but since hugepages only gives a 5% improvement taking the page size up probably will not dent it by more than an additional percent or so.
BTW I goofed on the kernel version number in my last post. It should be 2.6.39.4. That .27 was my mind transposing the 2.6.32 sub-version onto 2.6.39.
Have one closing thought, which is to wonder if the
9.98% swapper [kernel.kallsyms] [k] native_safe_halt
CPU is included in the 2.6.18(rhel) CPU accounting or not. If it's excluded that would make 2.6.39.4 look much better--possibly put it at near parity though I'm too lazy to do the math just now.
My guess is that this number is something of an artifact of the clock-tick CPU histogram logic. Perhaps it's seeing the IP register parked in the idle-loop HALT instruction some of the time and counting it as non-idle time. I'd be happier if it either counted all idle time and showed the 45% that the poll=idle run shows, or none of the idle time at all--if it is in fact idle time.
Unfortunately 'perf' is not available for 2.6.18(rhel) so the value cannot be compared.
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