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Re: external systemtap meeting notes 20070816
- From: Roland McGrath <roland at redhat dot com>
- To: "Frank Ch. Eigler" <fche at redhat dot com>
- Cc: systemtap at sources dot redhat dot com, utrace-devel at redhat dot com
- Date: Wed, 26 Sep 2007 13:33:56 -0700 (PDT)
- Subject: Re: external systemtap meeting notes 20070816
- References: <mailman.8592.1187789486.29635.external-perftools-list@redhat.com> <y0mlkc3k23c.fsf@ton.toronto.redhat.com> <mailman.3771.1188945116.11517.external-perftools-list@redhat.com> <y0mtzq9q3tf.fsf@ton.toronto.redhat.com> <20070926084229.B17714D04B7@magilla.localdomain> <20070926120115.GT8964@redhat.com>
> Would this hack work: have the second utrace engine refuse to put a
> breakpoint wherever it suspects another engine may have put one?
Sure, it's easy to notice the breakpoint instruction already there.
> Or even more pessimistically, can an engine know that another one is
> already monitoring a given target process, and give up at attach time?
> (That would defeat some of the promise of utrace, but so it goes.)
Yes, it can (UTRACE_ATTACH_EXCLUSIVE).
Thanks,
Roland