From: Joe Perches <joe@perches.com>
To: Markus Pargmann <mpa@pengutronix.de>
Cc: Marc Kleine-Budde <mkl@pengutronix.de>,
Wolfgang Grandegger <wg@grandegger.com>,
linux-can@vger.kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, kernel@pengutronix.de
Subject: Re: [PATCH v2] can: c_can: Speed up rx_poll function
Date: Tue, 29 Oct 2013 09:24:05 -0700 [thread overview]
Message-ID: <1383063845.2713.15.camel@joe-AO722> (raw)
In-Reply-To: <20131029085853.GC20839@pengutronix.de>
On Tue, 2013-10-29 at 09:58 +0100, Markus Pargmann wrote:
> On Tue, Oct 29, 2013 at 01:34:48AM -0700, Joe Perches wrote:
> > On Tue, 2013-10-29 at 09:27 +0100, Markus Pargmann wrote:
> > > This patch speeds up the rx_poll function by reducing the number of
> > > register reads.
> > []
> > > 125kbit:
> > > Function Hit Time Avg s^2
> > > -------- --- ---- --- ---
> > > c_can_do_rx_poll 63960 10168178 us 158.977 us 1493056 us
> > > With patch:
> > > c_can_do_rx_poll 63939 4268457 us 66.758 us 818790.9 us
> > >
> > > 1Mbit:
> > > Function Hit Time Avg s^2
> > > -------- --- ---- --- ---
> > > c_can_do_rx_poll 69489 30049498 us 432.435 us 9271851 us
> > > With patch:
> > > c_can_do_rx_poll 103034 24220362 us 235.071 us 6016656 us
[]
> Yes I just measured the timings again:
[]
> ./perf_can_test.sh 125000 30
[]
> c_can_do_rx_poll 63941 3764057 us 58.867 us 776162.2 us
Good, it's slightly faster still.
> ./perf_can_test.sh 1000000 30
[]
> c_can_do_rx_poll 207109 24322185 us 117.436 us 171469047 us
[]
> It is interesting that the number of hits for c_can_do_rx_poll is twice as much
> as it was with find_next_bit.
How is this possible? Any idea?
next prev parent reply other threads:[~2013-10-29 16:24 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-29 8:27 [PATCH v2] can: c_can: Speed up rx_poll function Markus Pargmann
2013-10-29 8:31 ` Joe Perches
[not found] ` <1383035688.2713.2.camel@joe-AO722>
2013-10-29 8:58 ` Markus Pargmann
2013-10-29 16:24 ` Joe Perches [this message]
2013-10-30 7:54 ` Markus Pargmann
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