From: Joel Fernandes <joel@joelfernandes.org>
To: "Paul E. McKenney" <paulmck@linux.ibm.com>
Cc: linux-kernel@vger.kernel.org, max.byungchul.park@gmail.com,
byungchul.park@lge.com, Davidlohr Bueso <dave@stgolabs.net>,
Josh Triplett <josh@joshtriplett.org>,
kernel-team@android.com, kernel-team@lge.com,
Lai Jiangshan <jiangshanlai@gmail.com>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Rao Shoaib <rao.shoaib@oracle.com>,
rcu@vger.kernel.org, Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH RFC v1 2/2] rcuperf: Add kfree_rcu performance Tests
Date: Fri, 9 Aug 2019 12:01:55 -0400 [thread overview]
Message-ID: <20190809160155.GA221383@google.com> (raw)
In-Reply-To: <20190807175657.GF28441@linux.ibm.com>
On Wed, Aug 07, 2019 at 10:56:57AM -0700, Paul E. McKenney wrote:
> On Wed, Aug 07, 2019 at 06:22:13AM -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:
> > > > This test runs kfree_rcu in a loop to measure performance of the new
> > > > kfree_rcu, with and without patch.
> > > >
> > > > To see improvement, run with boot parameters:
> > > > rcuperf.kfree_loops=2000 rcuperf.kfree_alloc_num=100 rcuperf.perf_type=kfree
> > > >
> > > > Without patch, test runs in 6.9 seconds.
> > > > With patch, test runs in 6.1 seconds (+13% improvement)
> > > >
> > > > If it is desired to run the test but with the traditional (non-batched)
> > > > kfree_rcu, for example to compare results, then you could pass along the
> > > > rcuperf.kfree_no_batch=1 boot parameter.
> > >
> > > You lost me on this one. You ran two runs, with rcuperf.kfree_no_batch=1
> > > and without? Or you ran this patch both with and without the earlier
> > > patch, and could have run with the patch and rcuperf.kfree_no_batch=1?
> >
> > I always run the rcutorture test with patch because the patch doesn't really
> > do anything if rcuperf.kfree_no_batch=0. This parameter is added so that in
> > the future folks can compare effect of non-batching with that of the
> > batching. However, I can also remove the patch itself and run this test
> > again.
> >
> > > If the latter, it would be good to try all three.
> >
> > Ok, sure.
>
> Very good! And please make the commit log more clear. ;-)
Sure will do :)
> > > > + long me = (long)arg;
> > > > + struct kfree_obj **alloc_ptrs;
> > > > + u64 start_time, end_time;
> > > > +
> > > > + VERBOSE_PERFOUT_STRING("kfree_perf_thread task started");
> > > > + set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
> > > > + set_user_nice(current, MAX_NICE);
> > > > + atomic_inc(&n_kfree_perf_thread_started);
> > > > +
> > > > + alloc_ptrs = (struct kfree_obj **)kmalloc(sizeof(struct kfree_obj *) * kfree_alloc_num,
> > > > + GFP_KERNEL);
> > > > + if (!alloc_ptrs)
> > > > + return -ENOMEM;
> > > > +
> > > > + start_time = ktime_get_mono_fast_ns();
> > >
> > > Don't you want to announce that you started here rather than above in
> > > order to avoid (admittedly slight) measurement inaccuracies?
> >
> > I did not follow, are you referring to the measurement inaccuracy related to
> > the "kfree_perf_thread task started" string print? Or, are you saying that
> > ktime_get_mono_fast_ns() has to start earlier than over here?
>
> I am referring to the atomic_inc().
Oh yes, great catch. I will increment closer to the test's actual start.
thanks!
> > (I will reply to the rest of the comments below in a bit, I am going to a
> > hospital now to visit a sick relative and will be back a bit later.)
>
> Ouch!!! I hope that goes as well as it possibly can! And please don't
> neglect your relative on RCU's account!!!
Thanks! it went quite well and now I am back to work ;-)
- Joel
next prev parent reply other threads:[~2019-08-09 16:01 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-06 21:20 [PATCH RFC v1 1/2] rcu/tree: Add basic support for kfree_rcu batching Joel Fernandes (Google)
2019-08-06 21:20 ` [PATCH RFC v1 2/2] rcuperf: Add kfree_rcu performance Tests Joel Fernandes (Google)
2019-08-07 0:29 ` Paul E. McKenney
2019-08-07 10:22 ` Joel Fernandes
2019-08-07 17:56 ` Paul E. McKenney
2019-08-09 16:01 ` Joel Fernandes [this message]
2019-08-11 2:01 ` Joel Fernandes
2019-08-11 23:42 ` Paul E. McKenney
2019-08-06 23:56 ` [PATCH RFC v1 1/2] rcu/tree: Add basic support for kfree_rcu batching Paul E. McKenney
2019-08-07 9:45 ` Joel Fernandes
2019-08-07 17:52 ` Paul E. McKenney
2019-08-08 9:52 ` Byungchul Park
2019-08-08 12:56 ` Joel Fernandes
2019-08-08 14:23 ` Byungchul Park
2019-08-08 18:09 ` Paul E. McKenney
2019-08-11 8:36 ` Byungchul Park
2019-08-11 8:49 ` Byungchul Park
2019-08-11 23:49 ` Paul E. McKenney
2019-08-12 10:10 ` Byungchul Park
2019-08-12 13:12 ` Joel Fernandes
2019-08-13 5:29 ` Byungchul Park
2019-08-13 15:41 ` Paul E. McKenney
2019-08-14 0:11 ` Byungchul Park
2019-08-14 2:53 ` Paul E. McKenney
2019-08-14 3:43 ` Byungchul Park
2019-08-14 16:59 ` Paul E. McKenney
2019-08-11 10:37 ` Byungchul Park
2019-08-08 23:30 ` Joel Fernandes
2019-08-09 15:16 ` Paul E. McKenney
2019-08-09 15:39 ` Joel Fernandes
2019-08-09 16:33 ` Paul E. McKenney
2019-08-09 20:22 ` Joel Fernandes
2019-08-09 20:26 ` Joel Fernandes
2019-08-09 21:25 ` Joel Fernandes
2019-08-10 3:38 ` Paul E. McKenney
2019-08-09 20:29 ` Joel Fernandes
2019-08-09 20:42 ` Paul E. McKenney
2019-08-09 21:36 ` Joel Fernandes
2019-08-10 3:40 ` Paul E. McKenney
2019-08-10 3:52 ` Joel Fernandes
2019-08-10 2:42 ` Joel Fernandes
2019-08-10 3:38 ` Paul E. McKenney
2019-08-10 4:20 ` Joel Fernandes
2019-08-10 18:24 ` Paul E. McKenney
2019-08-11 2:26 ` Joel Fernandes
2019-08-11 23:35 ` Paul E. McKenney
2019-08-12 13:13 ` Joel Fernandes
2019-08-12 14:44 ` Paul E. McKenney
2019-08-08 10:26 ` Byungchul Park
2019-08-08 18:11 ` Paul E. McKenney
2019-08-08 20:13 ` Joel Fernandes
2019-08-08 20:51 ` Paul E. McKenney
2019-08-08 22:34 ` Joel Fernandes
2019-08-08 22:37 ` Paul E. McKenney
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