MAXACTION exceeded error while using systemtap

[William Cohen]

Badari Pulavarty wrote:
> On Tue, 2005-12-06 at 11:59 -0500, Frank Ch. Eigler wrote:
> 
>>Badari Pulavarty <pbadari@us.ibm.com> writes:
>>
>>
>>>I am trying to collect pagecache usage info using systemtap
>>>and I get following error, while reporting. What should I 
>>>do fix it ?
>>>[...]
>>>ERROR: MAXACTION exceeded near embedded-code
>>>at /usr/local/share/systemtap/tapset/logging.stp:9:29
>>
>>See http://sourceware.org/bugzilla/show_bug.cgi?id=1866
> 
> 
> Okay, Thank you.
> 
> BTW, I am impressed with the NO (noticeable) overhead added 
> by having systemtap probes. Of course, I wasn't really doing
> a performance measurement. I was doing untars, kernel compiles
> with probes in add_to_page_cache() and remove_from_page() -
> which gets called a lot and didn't make much difference in the
> kernel compile time :)
> 
> 
> time with probe:
> (Totals PageAdd = 215326 PageDel = 17612)
> 
> real    3m40.492s
> user    5m44.894s
> sys     1m2.276s
> 
> time without probe:
> 
> real    3m40.085s
> user    5m45.650s
> sys     1m1.572s
> 
> 
> 
> 
> Thanks,
> Badari
> 

Assuming there is one probe fired per PageAdd and PageDel, there would 
be 232,938 probes fired during the experiment's 220 seconds. This would 
average 1059 probes per second. If one assumes about 1 microsecond 
overhead per probe (rough guestimage) that would be about .23 seconds 
over the run, pretty small.

-Will