From: Duyck, A. H <ale...@in...> - 2010-01-26 19:06:43
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Kelvin Ku wrote: > On Tue, Jan 26, 2010 at 01:20:12PM -0500, Kelvin Ku wrote: >> I've been conducting some more tests on the Xeon E5530 machine and >> discovered that "cpuspeed" was throttling the cores to 1.6 GHz. When >> I disabled cpuspeed, the clock speeds went back to the maximum, 2.4 >> GHz. However, when I did this, I started seeing high >> rx_missed_errors counts from the e1000e driver, which indicates that >> the NIC FIFO was overflowing. >> >> To remedy this, I passed the option "InterruptRateThrottle=0,0" to >> the driver to disable interrupt throttling and the rx_missed_errors >> counts went back to zero or nearly zero. >> >> Any idea why the NICs (82574L) would react like this to an increase >> in CPU clock speed? >> >> - Kelvin > > Oops, I meant "InterruptThrottleRate=0,0" above. > > - Kelvin I was wondering if you have any CPU Cn states, or ASPM enabled on any of the PCIe slots for the system? What you are describing sounds like it could be an issue with the CPU or PCIe links going to sleep and by the time they wake up you are already overrunning the NIC FIFO. If you cannot find any information in the BIOS you might try downloading and installing PowerTop (http://www.lesswatts.org/projects/powertop/) to check and see if CPU Cn states are being used. Other than that the only other thing I could recommend for the 82574 would be to modify the ".pba" value in the e1000_82574_info structure in the driver to be 36 by default instead of 20. This would increase the amount of RX FIFO available and should have no negative impact on TX performance. Thanks, Alex |