Messages in this thread |  | | Date | Fri, 23 Aug 2002 13:30:07 -0700 | From | Dave Hansen <> | Subject | Re: [Lse-tech] Re: (RFC): SKB Initialization |
| |
Bill Hartner wrote: > > 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. > > 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 must have misunderstood the data from the first email. I was under the impression that it was much smaller than that number.
>>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 ?
Mala's main complaint about readprofile is that it cannot profile while interrupts are disabled. oprofile's timer interrupts cannot be disabled, they _always_ occur.
> 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.
I look forward to seeing it.
>>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 ?
Mala's main complaint about readprofile is that it cannot profile while interrupts are disabled. I didn't see the case where it was being called with interrupts disabled. I was hoping that you could point it out to me.
-- Dave Hansen haveblue@us.ibm.com
- 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/
|  |