linux-kernel - Re: [Patch v3 0/6] Introduce LMh driver for Qualcomm SoCs

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Date:   Tue, 27 Jul 2021 11:29:15 -0400
From:   Thara Gopinath <thara.gopinath@...aro.org>
To:     Steev Klimaszewski <steev@...i.org>, agross@...nel.org,
        bjorn.andersson@...aro.org, rui.zhang@...el.com,
        daniel.lezcano@...aro.org, viresh.kumar@...aro.org,
        rjw@...ysocki.net, robh+dt@...nel.org
Cc:     tdas@...eaurora.org, mka@...omium.org,
        linux-arm-msm@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [Patch v3 0/6] Introduce LMh driver for Qualcomm SoCs



On 7/21/21 11:14 PM, Steev Klimaszewski wrote:
> Hi Thara!
> 
> On 7/8/21 7:06 AM, Thara Gopinath wrote:
>> Limits Management Hardware(LMh) is a hardware infrastructure on some
>> Qualcomm SoCs that can enforce temperature and current limits as programmed
>> by software for certain IPs like CPU. On many newer SoCs LMh is configured
>> by firmware/TZ and no programming is needed from the kernel side. But on
>> certain SoCs like sdm845 the firmware does not do a complete programming of
>> the h/w block. On such SoCs kernel software has to explicitly set up the
>> temperature limits and turn on various monitoring and enforcing algorithms
>> on the hardware.
>>
>> Introduce support for enabling and programming various limit settings and
>> monitoring capabilities of Limits Management Hardware(LMh) associated with
>> cpu clusters. Also introduce support in cpufreq hardware driver to monitor
>> the interrupt associated with cpu frequency throttling so that this
>> information can be conveyed to the schdeuler via thermal pressure
>> interface.
>>
>> With this patch series following cpu performance improvement(30-70%) is
>> observed on sdm845. The reasoning here is that without LMh being programmed
>> properly from the kernel, the default settings were enabling thermal
>> mitigation for CPUs at too low a temperature (around 70-75 degree C).  This
>> in turn meant that many a time CPUs were never actually allowed to hit the
>> maximum possible/required frequencies.
>>
>> UnixBench whets and dhry (./Run whets dhry)
>> System Benchmarks Index Score
>>
>>                  Without LMh Support             With LMh Support
>> 1 copy test     1353.7                          1773.2
>>
>> 8 copy tests    4473.6                          7402.3
>>
>> Sysbench cpu
>> sysbench cpu --threads=8 --time=60 --cpu-max-prime=100000 run
>>
>>                  Without LMh Support             With LMh Support
>> Events per
>> second                  355                             614
>>
>> Avg Latency(ms)         21.84                           13.02
>>
>> v2->v3:
>> 	- Included patch adding dt binding documentation for LMh nodes.
>> 	- Rebased to v5.13
>>
>> Thara Gopinath (6):
>>    firmware: qcom_scm: Introduce SCM calls to access LMh
>>    thermal: qcom: Add support for LMh driver
>>    cpufreq: qcom-cpufreq-hw: Add dcvs interrupt support
>>    arm64: boot: dts: qcom: sdm45: Add support for LMh node
>>    arm64: boot: dts: qcom: sdm845: Remove cpufreq cooling devices for CPU
>>      thermal zones
>>    dt-bindings: thermal: Add dt binding for QCOM LMh
>>
>>   .../devicetree/bindings/thermal/qcom-lmh.yaml | 100 ++++++++
>>   arch/arm64/boot/dts/qcom/sdm845.dtsi          | 162 ++----------
>>   drivers/cpufreq/qcom-cpufreq-hw.c             | 118 +++++++++
>>   drivers/firmware/qcom_scm.c                   |  58 +++++
>>   drivers/firmware/qcom_scm.h                   |   4 +
>>   drivers/thermal/qcom/Kconfig                  |  10 +
>>   drivers/thermal/qcom/Makefile                 |   1 +
>>   drivers/thermal/qcom/lmh.c                    | 239 ++++++++++++++++++
>>   include/linux/qcom_scm.h                      |  14 +
>>   9 files changed, 570 insertions(+), 136 deletions(-)
>>   create mode 100644 Documentation/devicetree/bindings/thermal/qcom-lmh.yaml
>>   create mode 100644 drivers/thermal/qcom/lmh.c
>>
> I've been using these patches on a 5.13 kernel
> (https://github.com/steev/linux/tree/linux-5.13.y - while trying to
> track down a different issue, while playing a video on youtube, as well
> as compressing a 9.2GB file with xz, I got the following

Hi Steev,

Thanks for testing this. I was unable to reproduce this. I have posted 
v4 moving the interrupt handling in qcom-cpufreq-hw to threaded 
interrupt handler and hopefully this should fix the issue. It will be 
great if you can test and let me know.

-- 
Warm Regards
Thara (She/Her/Hers)