Re: [RFC][PATCH] fs: optimize inotify/fsnotify code for unwatched files

From: Peter Zijlstra
Date: Mon Jun 22 2015 - 11:20:39 EST


On Mon, Jun 22, 2015 at 08:11:21AM -0700, Paul E. McKenney wrote:
> That depends on how slow the resulting slow global state would be.
> We have some use cases (definitely KVM, perhaps also some of the VFS
> code) that need the current speed, as opposed to the profound slowness
> that three trips through synchronize_sched() would provide.

But we have call_srcu() these days, not everything needs to use
sync_srcu() anymore. Although I've not checked recently.

> Plus we
> would lose the ability to have SRCU readers on idle and offline CPUs.

Are we actually doing that? offline CPUs in particular seems iffy, I
don't think we need (or should) worry about that. I know its been an
issue with regular RCU due to tracing, but I'm not sure we should care
for it for SRCU.
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