Questio on Gprof

[Peter Jeremy]

[Please wrap your lines before 80 columns]

On 2007-Feb-18 22:08:17 +0800, Mayank Kumar <mayank at microsoft.com> wrote:
>I want to know if gprof's profling is solely dependent on the system
>call profil() or are there other implementations of gprof which do
>not depend on this system call.

gprof has two sources of data: Firstly sampling information giving
number of hits by text address.  This information is collected by the
kernel - profil() just tells the kernel where to store the profiling
samples.  The second source is caller/callee counts collected by
.mcount in userland.

I am unaware of any alternative to profil() - in theory, it could
be implemented in userland but the overheads would be extremely high.

>Also is there a profiler available for freebsd or any unix system
>which is based on instrumentation rather then sampling.

gprof relies on both instrumentatin and sampling.  An alternative
would be gcov - though it reports line counts rather than execution
time statistics.

-- 
Peter Jeremy
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