Messages in this thread | | | Date | Tue, 17 Apr 2012 14:52:28 +0200 | From | Lesław Kopeć <> | Subject | Re: Inconsistent load average on tickless kernels |
| |
Hello!
I've finally finished testing patch c308b56b53. Apologies for the delay in reporting back. This time I've compared kernels from 3.2 and 2.6.32 branches. Here's a snapshot of load 15 on different versions:
2.6.32.55-hz-0f004f5a69 12.78 2.6.32.55-no-hz-74f5187ac8 4.42 2.6.32.55-no-hz-0f004f5a69 0.49 2.6.32.55-no-hz-c308b56b53 4.37 3.2.12-hz 12.85 3.2.12-no-hz 0.65 3.2.12-no-hz-c308b56b53 7.25 3.2.12-no-hz-c308b56b53 nohz=off 10.59
A whole day trend is available on a comparison chart [1].
Just to make things clear 2.6.32 kernels were patched as follows: * 74f5187ac8 - just 74f5187ac8 * 0f004f5a69 - 74f5187ac8 + 0f004f5a69 * c308b56b53 - 74f5187ac8 + 0f004f5a69 + c308b56b53
For kernel 3.2.12 patch c308b56b53 seems almost perfect. For low CPU utilization the load value is slightly lower for NO_HZ version than it is for HZ one. However the difference is small and the overall trend relates to CPU usage quite closely. This is definitely the best match so far. Thanks!
Looking at results for 2.6.32.55 branch it seems that we're back at 74f5187ac8 patch - the values are almost the same. The difference between NO_HZ and HZ versions is noticeable. At the risk of sounding like an ungrateful bastard - will there be further attempts at fixing this bug for 2.6.32 kernels?
[1] http://img535.imageshack.us/img535/2204/kernelload.png
-- Lesław Kopeć
[unhandled content-type:application/pgp-signature] | |