Messages in this thread | | | Subject | Re: WARNING in __mmdrop | From | Jason Wang <> | Date | Thu, 25 Jul 2019 22:25:25 +0800 |
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On 2019/7/25 下午9:26, Michael S. Tsirkin wrote: >> Exactly, and that's the reason actually I use synchronize_rcu() there. >> >> So the concern is still the possible synchronize_expedited()? > I think synchronize_srcu_expedited. > > synchronize_expedited sends lots of IPI and is bad for realtime VMs. > >> Can I do this >> on through another series on top of the incoming V2? >> >> Thanks >> > The question is this: is this still a gain if we switch to the > more expensive srcu? If yes then we can keep the feature on,
I think we only care about the cost on srcu_read_lock() which looks pretty tiny form my point of view. Which is basically a READ_ONCE() + WRITE_ONCE().
Of course I can benchmark to see the difference.
> if not we'll put it off until next release and think > of better solutions. rcu->srcu is just a find and replace, > don't see why we need to defer that. can be a separate patch > for sure, but we need to know how well it works.
I think I get here, let me try to do that in V2 and let's see the numbers.
Thanks
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