Messages in this thread | | | Date | Wed, 19 Aug 2009 09:50:12 -0400 | From | Mathieu Desnoyers <> | Subject | Re: [PATCH] tracing: Create generic syscall TRACE_EVENTs |
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* Ingo Molnar (mingo@elte.hu) wrote: > > * Josh Stone <jistone@redhat.com> wrote: > > > On 08/18/2009 06:32 PM, Li Zefan wrote: > > > It would be much better to see a sample output of these TRACE_EVENTs, > > > so we'll see the what's the output if a syscall has less than 6 args. > > > > > > And I guess it should be "(%lx, %lx, ..., %lx)"? Otherwise I think we'll > > > see some negative values. > > > > Thanks, you're right -- the args should be unsigned long. Whether they > > are hex or decimal doesn't matter to me, but I guess that does make > > pointers easier to spot. > > > > Here's some output that I get on x86_64: > > > > > # tail trace > > > tail-1106 [000] 113218.474657: syscall_enter: NR 2 (7f2d34dd38f0, 0, 7f2d35009010, 5, 4, ffffffffffffffb0) > > > > > > tail-1106 [000] 113218.474809: syscall_enter: NR 5 (3, 7f2d35009040, 7f2d35009040, 5, 4, ffffffffffffffb0) > > > > > > tail-1106 [000] 113218.474855: syscall_enter: NR 9 (0, 50d3ad0, 1, 2, 3, 0) > > > > > > tail-1106 [000] 113218.474946: syscall_enter: NR 3 (3, 7f2d2f9a0000, 5e22, 2, 3, 0) > > > > > > tail-1106 [000] 113218.475673: syscall_enter: NR 2 (7fff5e42a654, 0, 0, 7fff5e429600, 80, 3) > > > > It's very raw indeed, but that's what Ingo asked for. :) The > > extra args show up as whatever happened to be in those registers. > > If the syscalls are handled as a single tracepoint, then they > cannot really have per syscall properties. > > The per syscall tracepoints on the other hand give very finegrained > information. >
Hi Ingo,
Aiming to identify the event payload type with the event ID alone, I would recommend either:
- one tracepoint per syscall argument set types (e.g. same syscall prototype) or - one tracepoint per syscall (seems to be more straightforward)
Otherwise getting to fit a struct sockaddr into an integer might be cumbersome.
Thanks,
Mathieu
> Note that via the use of filters one can limit the generic > tracepoint to only output certain syscall NRs, and only with > certain parameters. > > Ingo
-- Mathieu Desnoyers OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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