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Re: MAXACTION exceeded error while using systemtap


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


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