Messages in this thread | ![/](/images/icornerl.gif) | | Subject | RE: ia64_do_page_fault shows 19.4% slowdown from notify_die. | Date | Tue, 18 Apr 2006 16:40:24 -0700 | From | "Luck, Tony" <> |
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> 499 nSec/fault ia64_do_page_fault notify_die commented out. > 501 nSec/fault ia64_do_page_fault with nobody registered. > 533 nSec/fault notify_die in and just kprobes. > 596 nSec/fault notify_die in and kdb, kprobes, mca, and xpc loaded. > > The 596 nSec/fault is a 19.4% slowdown. This is an upcoming OSD beta > kernel. It will be representative of what our typical customer will > have loaded. > > Is this enough justification for breaking notify_die into > notify_page_fault for the fault path?
I didn't see quite the stability from run to run that your results suggest. Running the benchmark five times on the same kernel, I saw the mean value of the 128 results go from as low as 439 to as high as 445. So the difference between commenting in/out the notify_die call is in the noise.
But comparing the first and last of your results shows that there is significant slowdown when the notify chain is loaded up with a ton of stuff, way more than the noise that I see, and I'm glad to see Anil jumping in to fix this.
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