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From: Jim Blandy <jimb@redhat.com>
To: Kevin Buettner <kevinb@redhat.com>
Cc: rda@sources.redhat.com
Subject: Re: [RFC] Improve performance of multi-threaded debugging
Date: Fri, 16 Sep 2005 20:13:00 -0000	[thread overview]
Message-ID: <m3irx0ydpa.fsf@alligator.red-bean.com> (raw)
In-Reply-To: <20050914150439.5a86df49@ironwood.lan> (Kevin Buettner's message of "Wed, 14 Sep 2005 15:04:39 -0700")


Kevin Buettner <kevinb@redhat.com> writes:
> As things stand now, the thread list is fetched each time rda checks
> the status of the program.  This doesn't sound like such a burden until
> you realize that some decent sized data structures are read via the
> ptrace() interface.  On slower machines, it can take a significant amount
> of time to single step or continue primarily due to this overhead.
>
> The patch below fetches the thread list only when it knows for certain
> that something has changed.
>
> The only fly in the ointment is that the signal based event model only
> knows about thread creation, but not about thread death.  So it won't
> catch thread death until some new thread is created.  I'm not sure
> what the implications of this are in practice.
>
> Comments?

Couldn't this be done dynamically?  That is, there are variables in
there that indicate whether we're using the signal-based model,
wherein I think we really do have to re-fetch the thread list all the
time, or the libthread_db-event-based model; wherein we don't.

  parent reply	other threads:[~2005-09-16 20:13 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-09-14 22:04 Kevin Buettner
2005-09-14 22:09 ` Daniel Jacobowitz
2005-09-14 22:31   ` Kevin Buettner
2005-09-16 20:13 ` Jim Blandy [this message]
2005-09-16 20:20 ` Jim Blandy
2005-09-16 20:49   ` Kevin Buettner
2005-09-17  0:19     ` Jim Blandy
2005-11-04 21:16 ` Kevin Buettner

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