Messages in this thread | | | Subject | Re: [PATCH] i386: Fix softirq accounting with 4K stacks | From | Mike Galbraith <> | Date | Mon, 26 Jun 2006 04:23:22 +0200 |
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On Sun, 2006-06-25 at 20:42 +0200, Björn Steinbrink wrote: > I just booted with both patches applied, mine and Mike's, and that > actually makes a difference in hardirq cpu time accounting. With my > patch only, hi is 0 in top while the box gets a ping flood. With both > patches, I get about 1% hi. Mike's patch causes update_process_times() > to be called twice on UP, but that alone shouldn't change the > percentages, right?
Yes, you definitely need to comment out the other call if you test the SMP path on UP+IO-APIC.
> OTOH top shows "hi" as zero with 8K stacks as well unless Mike's patch > is applied, so the results with Mike's patch are bogus (if so, why?) or > hardirq accounting is broken in general.
Something is certainly still b0rken. I still get three different answers to the question "what is my cpu usage" depending on configuration. With stock UP kernel with no IO-APIC, interrupt load is all hi. With your patch and IO-APIC, it's all si. SMP shows a mix of both.
I like the result of using the SMP path if you have an IO-APIC best, though I haven't verified them against a profile for accuracy. Taking a peek at the profile confirms that it is indeed mixed, so anything showing the load as being either hi or si has to be wrong.
-Mike
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