Date: Wed, 17 Jun 2015 17:24:00 -0700 From: Robert Mustacchi <rm@joyent.com> To: freebsd-dtrace@freebsd.org Subject: Re: Quantize a probe only if it has a particular function in its stack. Message-ID: <55820FA0.7090507@joyent.com> In-Reply-To: <ED346F16-DE50-4706-A8B9-89A7764649DD@gmail.com> References: <ED346F16-DE50-4706-A8B9-89A7764649DD@gmail.com>
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On 6/17/15 17:21 , Priyank Sanghavi wrote:
> Hello,
>
> I am currently working on dtrace on free-bsd. What I want to do is put a probe on uma_zalloc function and quantize its arguments. But along with that I want to keep a condition to quantize ( or record the readings) only if the stack of that uma_zalloc has a function ( foo ) in it. —— This means, consider the readings of uma_zalloc only if it has come from the function foo.
>
> Is there a condition that can do that work?
Just use a thread local variable that tracks when you enter the function
you care about and removes it when you return. eg. if you had a function
called foobar:
fbt::foobar:entry
{
self->t = 1;
}
fbt::foobar:return
{
self->t = 0;
}
Then you can use that as a predicate on an enabling of uma_zalloc.
Robert
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