Date: Thu, 20 May 2010 09:43:12 -0500 From: Dan McNulty <dkmcnulty@gmail.com> To: Alfred Perlstein <alfred@freebsd.org> Cc: freebsd-hackers@freebsd.org Subject: Re: Efficient way to determine when a child process forks or calls exec Message-ID: <AANLkTil8o-EvZlvDLYpnkyvTE2gr4mcRSXRGVsFpQO6m@mail.gmail.com> In-Reply-To: <20100519215139.GZ6175@elvis.mu.org> References: <AANLkTinO0hqywG7sCWJYXTsayOtad2qnP1SPDn6NzCYm@mail.gmail.com> <20100518074054.GE6175@elvis.mu.org> <AANLkTinjuqRKqwqDKBTyDiw7WmkE1-P5u8vTz7EBvqSJ@mail.gmail.com> <20100519215139.GZ6175@elvis.mu.org>
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On Wed, May 19, 2010 at 4:51 PM, Alfred Perlstein <alfred@freebsd.org> wrote: > * Dan McNulty <dkmcnulty@gmail.com> [100519 07:13] wrote: >> Thanks for all the great suggestions! >> >> It looks like the kevent system call is the closest to what I need. >> However, I didn't mention this, but I would like the process being >> traced to be stopped on entrance to fork, exec, etc. This would be >> similar to Linux's ptrace interface which sends a SIGTRAP to the >> traced process on exec, fork, etc. From what I could tell so far, >> kevent doesn't provide this functionality. >> >> Am I missing something? Is there a way to get kevent to stop the >> process when events occur? > > Not that I know of off the top of my head. > > Although if you want to contrib the code I can help get it in. :) > > -Alfred Unfortunately, writing a patch for the FreeBSD kernel may be beyond the scope of my current work. Although I wouldn't mind working on it in my spare time outside of my job. Maybe in some free time this summer. I think the ideal fix for my problem would be to implement a mechanism similar to the Linux ptrace interface that sends a SIGTRAP for events such as fork, exec, thread create, etc. Maybe I will poke around in the FreeBSD kernel source and see what I can figure out. Thanks for the help! -Dan >> >> Thanks again for your help, >> -Dan >> >> On Tue, May 18, 2010 at 2:40 AM, Alfred Perlstein <alfred@freebsd.org> wrote: >> > * Dan McNulty <dkmcnulty@gmail.com> [100517 08:02] wrote: >> >> Hi all, >> >> >> >> I have been experimenting with ptrace to determine when a child >> >> process forks or calls exec. Particularly, I have explored tracing >> >> every system call entry and exit similar to what the truss utility >> >> does, and for my case, the performance impact of tracing every system >> >> call is too great. >> >> >> >> Is there a more efficient way than tracing every system call entry and >> >> exit to determine when a child process forks, calls exec, or creates a >> >> new LWP? >> >> >> >> Thanks a lot for your help! >> > >> > kevent has some hooks, have you looked at that? >> > >> > -- >> > - Alfred Perlstein >> > .- AMA, VMOA #5191, 03 vmax, 92 gs500, 85 ch250, 07 zx10 >> > .- FreeBSD committer >> > > > -- > - Alfred Perlstein > .- AMA, VMOA #5191, 03 vmax, 92 gs500, 85 ch250, 07 zx10 > .- FreeBSD committer >
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