Re: [SCRIPT] NUMA page fault accounting.

["Jose R. Santos" <jrs at us dot ibm dot com>]

Stone, Joshua I wrote:

> Jose R. Santos wrote:
> >         page_faults [pid(), $write_access ? 1 : 0] ++
> >         node_faults [pid(), addr_to_node($address)] ++
>
> You could improve scalability of this script by using statistics to
> maintain your count, e.g.:
>
>         page_faults [pid(), $write_access ? 1 : 0] <<< 1
>         node_faults [pid(), addr_to_node($address)] <<< 1
>
> And then access the values with @count(page_faults[...]).
>
> Other than that, this looks good.  It might be nice to start publishing
> case studies on the website, so if you have a real problem that you
> solved with this, please share!
>
>
> Josh
>  
Here the updated script based on your suggestions.  Unfortunately, the 
machine that I uses is an old pre-production box that gives me a lot of 
variability between runs even when Im not running the SystemTap script 
so I cant verify if the changes are faster running the stream benchmark.

Thanks

-JRS

#! /usr/local/bin/stap -g

global execnames, page_faults, node_faults

function addr_to_node:long(addr:long)
%{
       int nid;
       int pfn = __pa(THIS->addr) >> PAGE_SHIFT;
       for_each_online_node(nid)
               if ( node_start_pfn(nid) <= pfn &&
                       pfn < (node_start_pfn(nid) +
                       NODE_DATA(nid)->node_spanned_pages) )
               {
                       THIS->__retvalue = nid;                
                       break;
               }

%}

probe kernel.function("__handle_mm_fault") {
       execnames[pid()] = execname()
       page_faults [pid(), $write_access ? 1 : 0] <<< 1
       node_faults [pid(), addr_to_node($address)] <<< 1

}

function print_pf () {
       print ("            Execname\t     PID\tRead Faults\tWrite 
Faults\n")
       print 
("====================\t========\t===========\t============\n")
       foreach (pid in execnames) {
               printf ("%20s\t%8d\t%11d\t%12d\t", execnames[pid], pid,
                       @count(page_faults[pid,0]), 
@count(page_faults[pid,1]))

               foreach ([pid2,node+] in node_faults) {
                       if (pid2 == pid)
                               printf ("Node[%d]=%d\t", node,
                                       @count(node_faults[pid2, node]))
               }
               print ("\n")

       }
}

probe begin {
 print ("Starting pagefault counters \n")
}

probe end {
 print ("Printing counters: \n")
 print_pf ()
 print ("Done\n")
}