From: Charles Keepax <ckeepax@opensource.cirrus.com>
To: Jon Hunter <jonathanh@nvidia.com>
Cc: Liam Girdwood <lgirdwood@gmail.com>,
Mark Brown <broonie@kernel.org>, Jaroslav Kysela <perex@perex.cz>,
Takashi Iwai <tiwai@suse.com>, <linux-tegra@vger.kernel.org>,
<alsa-devel@alsa-project.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [alsa-devel] [PATCH] ASoC: core: Don't schedule DAPM work if already in target state
Date: Tue, 28 Aug 2018 11:39:11 +0100 [thread overview]
Message-ID: <20180828103911.GX32322@imbe.wolfsonmicro.main> (raw)
In-Reply-To: <1534520143-29266-1-git-send-email-jonathanh@nvidia.com>
On Fri, Aug 17, 2018 at 04:35:43PM +0100, Jon Hunter wrote:
> When dapm_power_widgets() is called, the dapm_pre_sequence_async() and
> dapm_post_sequence_async() functions are scheduled for all DAPM contexts
> (apart from the card DAPM context) regardless of whether the DAPM
> context is already in the desired state. The overhead of this is not
> insignificant and the more DAPM contexts there are the more overhead
> there is.
>
> For example, on the Tegra124 Jetson TK1, when profiling the time taken
> to execute the dapm_power_widgets() the following times were observed.
>
> Times for function dapm_power_widgets() are (us):
> Min 23, Ave 190, Max 434, Count 39
>
> Here 'Count' is the number of times that dapm_power_widgets() has been
> called. Please note that the above time were measured using ktime_get()
> to log the time on entry and exit from dapm_power_widgets(). So it
> should be noted that these times may not be purely the time take to
> execute this function if it is preempted. However, after applying this
> patch and measuring the time taken to execute dapm_power_widgets() again
> a significant improvement is seen as shown below.
>
> Times for function dapm_power_widgets() are (us):
> Min 4, Ave 16, Max 82, Count 39
>
> Therefore, optimise the dapm_power_widgets() function by only scheduling
> the dapm_pre/post_sequence_async() work if the DAPM context is not in
> the desired state.
>
> Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
> ---
Looks ok to me:
Reviewed-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Although that said the performance increase is pretty hard to
measure on my systems.
Thanks,
Charles
next prev parent reply other threads:[~2018-08-28 10:39 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-17 15:35 [PATCH] ASoC: core: Don't schedule DAPM work if already in target state Jon Hunter
2018-08-28 10:39 ` Charles Keepax [this message]
2018-09-03 14:45 ` [alsa-devel] " Jon Hunter
2018-09-03 14:19 ` Applied "ASoC: core: Don't schedule DAPM work if already in target state" to the asoc tree Mark Brown
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