Messages in this thread | | | Date | Tue, 4 Jul 2006 13:41:45 +0200 (CEST) | From | Jesper Dangaard Brouer <> | Subject | Re: Network performance degradation from 2.6.11.12 to 2.6.16.20 |
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On Mon, 26 Jun 2006, Andi Kleen wrote:
>> I encountered the same problem on a dual core opteron equipped with a >> broadcom NIC (tg3) under 2.4. It could receive 1 Mpps when using TSC >> as the clock source, but the time jumped back and forth, so I changed >> it to 'notsc', then the performance dropped dramatically to around the >> same value as above with one CPU saturated. I suspect that the clock >> precision is needed by the tg3 driver to correctly decide to switch to >> polling mode, but unfortunately, the performance drop rendered the >> solution so much unusable that I finally decided to use it only in >> uniprocessor with TSC enabled. > > 2.6 is more clever at this than 2.4. In particular it does the timestamp > for each packet only when actually needed, which is relativelt rare. > > Old experiences do not always apply to new kernels.
Note, that I experinced this problem on 2.6.
Actually the change happens between kernel version 2.6.15 and 2.6.16. And is a result of Andi's changes to arch/x86_64/Kconfig and drivers/acpi/Kconfig, which "allows/activates" the use of the timer on x86_64.
Cheers, Jesper Brouer
-- ------------------------------------------------------------------- MSc. Master of Computer Science Dept. of Computer Science, University of Copenhagen Author of http://www.adsl-optimizer.dk ------------------------------------------------------------------- - 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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