linux-kernel - Re: [PATCH RFC v1 2/2] rcuperf: Add kfree

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Date:   Sun, 11 Aug 2019 16:42:05 -0700
From:   "Paul E. McKenney" <paulmck@...ux.ibm.com>
To:     Joel Fernandes <joel@...lfernandes.org>
Cc:     linux-kernel@...r.kernel.org, max.byungchul.park@...il.com,
        byungchul.park@....com, Davidlohr Bueso <dave@...olabs.net>,
        Josh Triplett <josh@...htriplett.org>, kernel-team@...roid.com,
        kernel-team@....com, Lai Jiangshan <jiangshanlai@...il.com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Rao Shoaib <rao.shoaib@...cle.com>, rcu@...r.kernel.org,
        Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [PATCH RFC v1 2/2] rcuperf: Add kfree_rcu performance Tests

On Sat, Aug 10, 2019 at 10:01:54PM -0400, Joel Fernandes wrote:
> On Tue, Aug 06, 2019 at 05:29:15PM -0700, Paul E. McKenney wrote:
> > On Tue, Aug 06, 2019 at 05:20:41PM -0400, Joel Fernandes (Google) wrote:

[ . . . ]

> > It is really easy to confuse "l" and "1" in some fonts, so please use
> > a different name.  (From the "showing my age" department:  On typical
> > 1970s typewriters, there was no numeral "1" -- you typed the letter
> > "l" instead, thus anticipating at least the first digit of "1337".)
> 
> Change l to loops ;). I did see typewriters around in my childhood, I thought
> they were pretty odd machines :-D. I am sure my daughter will think the same
> about land-line phones :-D

Given your daughter's life expectancy, there will likely be a great many
ca-2019 artifacts that will eventually seem quite odd to her.  ;-)

[ . . . ]

> > > +/*
> > > + * shutdown kthread.  Just waits to be awakened, then shuts down system.
> > > + */
> > > +static int
> > > +kfree_perf_shutdown(void *arg)
> > > +{
> > > +	do {
> > > +		wait_event(shutdown_wq,
> > > +			   atomic_read(&n_kfree_perf_thread_ended) >=
> > > +			   kfree_nrealthreads);
> > > +	} while (atomic_read(&n_kfree_perf_thread_ended) < kfree_nrealthreads);
> > > +
> > > +	smp_mb(); /* Wake before output. */
> > > +
> > > +	kfree_perf_cleanup();
> > > +	kernel_power_off();
> > > +	return -EINVAL;
> > > +}
> > 
> > Is there some way to avoid (almost) duplicating rcu_perf_shutdown()?
> 
> At the moment, I don't see a good way to do this without passing in function
> pointers or using macros which I think would look uglier than the above
> addition. Sorry.

No problem, just something to keep in mind.

							Thanx, Paul