linux-kernel - Re: call_rcu from trace

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Date:	Tue, 16 Jun 2015 18:04:39 -0700
From:	Alexei Starovoitov <ast@...mgrid.com>
To:	Steven Rostedt <rostedt@...dmis.org>
CC:	Daniel Wagner <wagi@...om.org>, paulmck@...ux.vnet.ibm.com,
	Daniel Wagner <daniel.wagner@...-carit.de>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: call_rcu from trace_preempt

On 6/16/15 5:47 PM, Steven Rostedt wrote:
> Do what I do in tracing. Use a bit (per cpu?) test.
>
> Add the element to the list (that will be a cmpxchg, but I'm not sure
> you can avoid it), then check the bit to see if the irq work is already
> been activated. If not, then activate the irq work and set the bit.
> Then you will not have any more cmpxchg in the fast path.

you mean similar to what rb_wakeups() and friends are doing?
makes sense. starting to study it...

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