improving replay performance

Chris Jones jones.chris.g at
Fri Nov 20 23:22:08 UTC 2015

On Fri, Nov 20, 2015 at 3:06 PM, Robert O'Callahan <robert at>

> On Sat, Nov 21, 2015 at 12:00 PM, Chris Jones <jones.chris.g at>
> wrote:
>> On Thu, Nov 19, 2015 at 6:32 PM, Robert O'Callahan <robert at>
>> wrote:
>>> * After we've replayed a set of buffered syscalls, we need to induce a
>>> ptrace stop so that rr can regain control and begin replaying the following
>>> event. I've thought of many ways to do this, none of which are wholly
>>> satisfying.
>> ​I don't quite understand the problem here ... since the buffer flush
>> (virtual event) was triggered by the next (real) event, can't we just
>> discard the buffer flush event after restoring the saved data and start
>> replaying the next one?​
> In most cases, yes, but sometimes after flushing the last event we need to
> set the notify_on_syscall_hook_exit flag.

​Ah, that's a new one for me :).  How about recording an event when you set
the flag during recording?

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