Re: dtrace, profile and ustack
Re: dtrace, profile and ustack
- Subject: Re: dtrace, profile and ustack
- From: Eric Gouriou <email@hidden>
- Date: Mon, 24 Aug 2009 17:51:55 -0700
On Aug 24, 2009, at 4:02 PM, Joel Reymont wrote:
I get a bunch of memory access errors when trying to run my script,
e.g.
dtrace: script 'high.d' matched 2 probes
dtrace: allowing destructive actions
dtrace: error on enabled probe ID 1 (ID 36: profile:::profile-997):
invalid address (0xbffff7c8) in action #2
dtrace: error on enabled probe ID 1 (ID 36: profile:::profile-997):
invalid address (0xbfffca28) in action #2
dtrace: error on enabled probe ID 1 (ID 36: profile:::profile-997):
invalid address (0xbfffcb58) in action #2
The script is trying to determine the hot paths through
initialization of firefox (up to main), e.g.
profile-997
/pid == $target/
{
@[ustack()] = count()
}
/* stop tracing here */
pid$target:XUL:XRE_main:entry
{
exit(0);
}
END
{
trunc(@, 25)
}
Any suggestions on how to avoid the non-paged memory errors above?
I'd recommend using Instruments and/or Shark for such profiles. The
DTrace profile
probe cannot give you this information at this time, as ustack() is
not effective from
the environment where profile probes get triggered. If I remember
correctly
that's due to not being able to take page faults in that environment.
Don't forget to file a bug report about this.
Eric
PS: <email@hidden> might be a better place to
hit
people more specialized towards performance work.
Thanks, Joel
---
fastest mac firefox!
http://wagerlabs.com
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