Re: [PATCH v3] rcu: Add a minimum time for marking boot as completed

Frederic Weisbecker
2023-03-08T15:01:20Z

On Wed, Mar 08, 2023 at 05:52:50AM -0800, Joel Fernandes wrote:
> Just to add to previous reply:
>
> One thing to consider is that it is more of a performance improvement for
> booting in expedited mode to fallback to normal later, than a bug
> fix. Repeated synchronize_rcu() can easily add 100s of milliseconds and to
> remedy that — a conversion of the call from normal API to the expedited API
> will not help.

2 things to consider:

1) Is it this about specific calls to synchronize_rcu() that repeat a lot
and thus create such measurable impact? If so the specific callsites should
be considered for a conversion.

2) Is it about lots of different calls to synchronize_rcu() that gather a big
noise? Then the solution is different.

Again without proper analysis, what do we know?

Thanks.