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RE: [PATCH 17/17] infrun: scheduler-locking reverse
- From: "Metzger, Markus T" <markus dot t dot metzger at intel dot com>
- To: Jan Kratochvil <jan dot kratochvil at redhat dot com>, Pedro Alves <palves at redhat dot com>
- Cc: "gdb-patches at sourceware dot org" <gdb-patches at sourceware dot org>
- Date: Tue, 15 Sep 2015 09:28:36 +0000
- Subject: RE: [PATCH 17/17] infrun: scheduler-locking reverse
- Authentication-results: sourceware.org; auth=none
- References: <1441794909-32718-1-git-send-email-markus dot t dot metzger at intel dot com> <1441794909-32718-18-git-send-email-markus dot t dot metzger at intel dot com> <55F03A12 dot 80307 at redhat dot com> <20150912194344 dot GA7575 at host1 dot jankratochvil dot net>
> -----Original Message-----
> From: Jan Kratochvil [mailto:jan.kratochvil@redhat.com]
> Sent: Saturday, September 12, 2015 9:44 PM
> To: Pedro Alves
> Cc: Metzger, Markus T; gdb-patches@sourceware.org
> Subject: Re: [PATCH 17/17] infrun: scheduler-locking reverse
Hello Jan,
> Thanks for bringing it up. I would have hard time mergin this patch's:
> -static const char *scheduler_mode = schedlock_off;
> +static const char *scheduler_mode = schedlock_reverse;
> with
> http://pkgs.fedoraproject.org/cgit/gdb.git/tree/gdb-6.6-scheduler_locking-
> step-is-default.patch
> -static const char *scheduler_mode = schedlock_off;
> +static const char *scheduler_mode = schedlock_step;
I don't believe that we need to preserve the current behaviour. If Fedora
defaults to schedlock_step, why not also for record targets?
It could be seen as bug-fix that record targets did not honour scheduler-locking.
The same holds for mainline, of course. But the new mode is much closer to
schedlock_step than it is to schedlock_off.
> My guess is there could be a new setting "set reverse-scheduler-locking" also
> with "off/step/on" as it seems to me "step" also makes sense for the
> scheduler
> locking in reverse mode.
This would allow us to set different scheduler-locking modes for reverse/replay
execution and for normal debugging. While this adds flexibility, I'm not sure it is
actually needed.
I really only added the new mode because I did not want to change the default
behaviour completely. Over time, I think we may want to deprecate it, even
though schedlock_off isn't very useful with the usually quite short execution
history. Maybe mainline will default to schedlock_step one day, as well?
Regards,
Markus.
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