Re: [DynInst_API:] Ignore certain signals

[Victor van der Veen <vvdveen@xxxxxxxxx>]

Hi Xiaozhu,

Thanks. Yes, I can do that for nodejs. However, the prevalent use is case SIGV: I insert instrumentation that will trigger segmentation faults. These are then handled by a custom signal handler (also added by my instrumentation). There may be many of these signals at run-time, and I don't want to pay for the extra ptrace/Dyninst overhead. This might be a ptrace limitation, and simply not possible though.

Best,

Vitor

On 1 May 2018 at 16:15, Xiaozhu Meng <mxz297@xxxxxxxxx> wrote:

Hi Victor,

Can you profile what signals are causing the slowdown? Dyninst uses a few different signals such as SIGSTOP, SIGTRAP, SIGUSR1, and SIGUSR2, for different purposes. Depending on which signal or signals are causing the problem, we may be able to figure out a way to let Dyninst not act on those signals.

Thanks,

--Xiaozhu

On Tue, May 1, 2018 at 8:07 AM, Victor van der Veen <vvdveen@xxxxxxxxx> wrote:

Hello,

Can I modify Dyninst's process control (for Linux) so that whenever a mutator remains attached to its mutatee, certain signals are delivered to the mutatee only?

I am instrumenting a binary (node.js) that triggers many signals during one of its benchmarks and I have the impression that this is causing a modest slowdown, as well as some weird memory leak. It would be great if I could tell Dyninst to not act on those signals.

Apologies for not reading the ptrace manual first :-)

Best regards,

Victor van der Veen

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