Messages in this thread |  | | Date | Fri, 23 Aug 2002 15:12:40 -0500 | From | Bill Hartner <> | Subject | Re: [Lse-tech] Re: (RFC): SKB Initialization |
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Dave Hansen wrote: > > Mala Anand wrote: > > Readprofile ticks are not as accurate as the cycles I measured. > > Moreover readprofile can give misleading information as it profiles > > on timer interrupts. The alloc_skb and __kfree_skb call memory > > management routines and interrupts are disabled in many parts of that code. > > So I don't trust the readprofile data. > > I don't believe your results to be accurate. They may be _precise_ > for a small case, but you couldn't have been measuring them for very > long. A claim of accuracy requires a large number of samples, which > you apparently did not do.
Dave,
What is your definition of a "very long time" ?
Read the 1st email. There were 2.4 million samples.
How many do you think is sufficient ?
> > I can't use oprofile or other NMI-based profilers on my hardware, so > we'll just have to guess. Is there any chance that you have access to > a large Specweb setup on hardware that is close to mine and can run > oprofile?
Why do you think oprofile is a better way to measure this ? BTW, Mala works with Troy Wilson who is running SPECweb99 on an 8-way system using Apache. Troy has run with Mala's patch and that data will be posted.
> > Where are interrupts disabled? I just went through a set of kernprof > data and traced up the call graph. In the most common __kfree_skb > case, I do not believe that it has interupts disabled. I could be > wrong, but I didn't see it.
What is the revelance of the above ?
> > http://www.sr71.net/~specweb99/old/run-specweb-2300-nodynpost-2.5.31-bk+profilers-08-14-2002-02.19.22/callgraph > > The end result, as I can see it, is that your patches hurt Specweb > performance.
Based on what ? A callgraph ? A profile ?
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