Messages in this thread | | | Date | Fri, 24 May 2019 08:57:44 -0400 | From | Steven Rostedt <> | Subject | Re: [RFC][PATCH 03/14 v2] function_graph: Allow multiple users to attach to function graph |
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On Fri, 24 May 2019 14:27:24 +0200 Peter Zijlstra <peterz@infradead.org> wrote:
> > Believe me, I rather not have that array, but I couldn't come up with a > > better solution to handle freeing of fgraph_ops. > > The trivial answer would be to refcount the thing, but can't we make > rcu_tasks do this?
But wouldn't refcounts require atomic operations, something that would be excruciatingly slow for something that runs on all functions.
rcu_tasks doesn't cross voluntary sleeps, which this does.
> > And delay the unreg until all active users are gone -- who gives a crap > that can take a while.
It could literally be forever (well, until the machine reboots). And something that could appear to be a memory leak, although a very slow one. But probably be hard to have more than the number of tasks on the system.
-- Steve
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