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Mon, 11 Mar 2019 01:24:21 -0700 (PDT) Received: from giga-mm ([62.68.22.49]) by smtp.gmail.com with ESMTPSA id v2sm24882187wme.29.2019.03.11.01.24.20 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Mon, 11 Mar 2019 01:24:21 -0700 (PDT) Date: Mon, 11 Mar 2019 09:24:20 +0100 From: Alexander Sverdlin To: Oleksij Rempel Cc: Greg Kroah-Hartman , Jiri Slaby , Pengutronix Kernel Team , linux-kernel@vger.kernel.org Subject: Re: [PATCH v1 3/3] drivers/tty: increase priority for tty_buffer_worker Message-Id: <20190311092420.7f57b8e4e3420de225213367@gmail.com> In-Reply-To: <20190110101232.9398-4-o.rempel@pengutronix.de> References: <20190110101232.9398-1-o.rempel@pengutronix.de> <20190110101232.9398-4-o.rempel@pengutronix.de> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.32; x86_64-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Oleksij, On Thu, 10 Jan 2019 11:12:32 +0100 Oleksij Rempel wrote: > sched_priority = 1 is enough to dramatically reduce latency > on have system load produced by tasks with default user space prio. > > Signed-off-by: Oleksij Rempel Tested-by: Alexander Sverdlin > --- > drivers/tty/tty_buffer.c | 12 +++++++++++- > 1 file changed, 11 insertions(+), 1 deletion(-) > > diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c > index 18bd7f48a319..7cf42f6570a0 100644 > --- a/drivers/tty/tty_buffer.c > +++ b/drivers/tty/tty_buffer.c > @@ -13,11 +13,13 @@ > #include > #include > #include > +#include > #include > #include > #include > #include > #include > +#include > > > #define MIN_TTYB_SIZE 256 > @@ -567,7 +569,15 @@ bool tty_buffer_queue_work(struct tty_port *port) > > void tty_buffer_init_kthread(void) > { > - kthread_run(kthread_worker_fn, &tty_buffer_worker, "tty"); > + struct sched_param param = { .sched_priority = 1 }; > + struct task_struct *kworker_task; > + > + kworker_task = kthread_run(kthread_worker_fn, &tty_buffer_worker, "tty"); > + if (IS_ERR(kworker_task)) { > + pr_err("failed to create message pump task\n"); > + return; > + } > + sched_setscheduler(kworker_task, SCHED_FIFO, ¶m); > } > > /** -- Alexander Sverdlin.