From: Alexandre Courbot <acourbot@nvidia.com>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: <linux-pm@vger.kernel.org>, <linux-tegra@vger.kernel.org>,
<linux-kernel@vger.kernel.org>, <gnurou@gmail.com>,
Alexandre Courbot <acourbot@nvidia.com>
Subject: [PATCH RFC] Revert "cpufreq: dt: Identify cpu-sharing for platforms without operating-points-v2"
Date: Thu, 16 Jun 2016 14:35:24 +0900 [thread overview]
Message-ID: <20160616053524.19921-1-acourbot@nvidia.com> (raw)
This is not an actual request for revert, but rather for comments about
the observed behavior since I am not really familiar with cpufreq.
I am observing a serious performance regression on Jetson TK1 since 4.7-rc1:
namely, moving windows under X would become unsufferably slow, and graphical
performance under X in general is seriously degraded. After bisecting, I
found the regression to be visible since commit 1530b9963eeb ("cpufreq: dt:
Identify cpu-sharing for platforms without operating-points-v2")
If I revert this commit, I noticed that the CPU frequency immediately jumps to
a higher frequency once I start moving windows (resulting in a smooth and
responsive action), whereas enabling this commit causes the CPU frequency to
remain low (typically 204 Mhz) in that case, resulting in CPU-bound slowness.
What happens is that with 1530b9963eeb applied, dev_pm_opp_get_sharing_cpus()
returns zero causing the fallback variable to remain false, whereas without it
opp_v1 is set to true.
It is not clear to me whether this is a cpufreq issue or a Tegra issue, so I am
posting this in the hope to get clarifications from either side.
Thanks!
---
drivers/cpufreq/cpufreq-dt.c | 16 +++++++---------
1 file changed, 7 insertions(+), 9 deletions(-)
diff --git a/drivers/cpufreq/cpufreq-dt.c b/drivers/cpufreq/cpufreq-dt.c
index 3957de801ae8..eef245cd4b7f 100644
--- a/drivers/cpufreq/cpufreq-dt.c
+++ b/drivers/cpufreq/cpufreq-dt.c
@@ -146,7 +146,7 @@ static int cpufreq_init(struct cpufreq_policy *policy)
struct clk *cpu_clk;
struct dev_pm_opp *suspend_opp;
unsigned int transition_latency;
- bool fallback = false;
+ bool opp_v1 = false;
const char *name;
int ret;
@@ -166,16 +166,14 @@ static int cpufreq_init(struct cpufreq_policy *policy)
/* Get OPP-sharing information from "operating-points-v2" bindings */
ret = dev_pm_opp_of_get_sharing_cpus(cpu_dev, policy->cpus);
if (ret) {
- if (ret != -ENOENT)
- goto out_put_clk;
-
/*
* operating-points-v2 not supported, fallback to old method of
- * finding shared-OPPs for backward compatibility if the
- * platform hasn't set sharing CPUs.
+ * finding shared-OPPs for backward compatibility.
*/
- if (dev_pm_opp_get_sharing_cpus(cpu_dev, policy->cpus))
- fallback = true;
+ if (ret == -ENOENT)
+ opp_v1 = true;
+ else
+ goto out_put_clk;
}
/*
@@ -215,7 +213,7 @@ static int cpufreq_init(struct cpufreq_policy *policy)
goto out_free_opp;
}
- if (fallback) {
+ if (opp_v1) {
cpumask_setall(policy->cpus);
/*
--
2.8.3
next reply other threads:[~2016-06-16 5:35 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-16 5:35 Alexandre Courbot [this message]
2016-06-16 6:35 ` [PATCH RFC] Revert "cpufreq: dt: Identify cpu-sharing for platforms without operating-points-v2" Viresh Kumar
2016-06-16 6:57 ` Alexandre Courbot
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20160616053524.19921-1-acourbot@nvidia.com \
--to=acourbot@nvidia.com \
--cc=gnurou@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pm@vger.kernel.org \
--cc=linux-tegra@vger.kernel.org \
--cc=viresh.kumar@linaro.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).