Re: [PATCH v5 7/7] Documentation:cpufreq:boost: Update BOOST documentation
On Wed, 17 Jul 2013 13:29:26 +0530 Viresh Kumar viresh.ku...@linaro.org wrote, > On 17 July 2013 13:06, Lukasz Majewski wrote: > > At v4 there was the old acpi-cpufreq.c behaviour preserved (with > > always exporting boost - when not supported ro, when supported rw). > > > > Due to Rafael and Dirk comments it has been rewritten at v5: > > > > http://thread.gmane.org/gmane.linux.kernel/1511831/match=patch+v4+2+7+cpufreq+add+boost+frequency+support+core > > > > > >> > >> Rafael Said: > >> "Simple: Export it only when supported." > > [*] > > > >> > >> AND > >> > >> "Don't change behavior of acpi-cpufreq driver" > > [**] > >> > >> If you see acpi-cpufreq driver carefully, it always creates "boost" > >> sysfs entry. If its not supported then it creates a read only > >> entry. > > > > For me those two statements [*] and [**] contradict: > > > > At v5: > > 1. ARM - export "boost" only when supported (rw) > > 2. x86 - export boost only when x86 supports it (as rw). When x86 > > doesn't support HW boost - DO NOT export it at all. > > > > At v4: > > 1. ARM - export "boost" only when supported (rw) > > 2. x86 - always export boost - no matter if supported or not. If not > > supported, then export it as ro only. > > Okay, there is some confusion.. > > I have raised a query on your v4 mail.. lets see what people have to > say. Ok. -- Best regards, Lukasz Majewski Samsung R&D Institute Poland (SRPOL) | Linux Platform Group -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v5 7/7] Documentation:cpufreq:boost: Update BOOST documentation
On 17 July 2013 13:06, Lukasz Majewski wrote: > At v4 there was the old acpi-cpufreq.c behaviour preserved (with always > exporting boost - when not supported ro, when supported rw). > > Due to Rafael and Dirk comments it has been rewritten at v5: > > http://thread.gmane.org/gmane.linux.kernel/1511831/match=patch+v4+2+7+cpufreq+add+boost+frequency+support+core > > >> >> Rafael Said: >> "Simple: Export it only when supported." > [*] > >> >> AND >> >> "Don't change behavior of acpi-cpufreq driver" > [**] >> >> If you see acpi-cpufreq driver carefully, it always creates "boost" >> sysfs entry. If its not supported then it creates a read only entry. > > For me those two statements [*] and [**] contradict: > > At v5: > 1. ARM - export "boost" only when supported (rw) > 2. x86 - export boost only when x86 supports it (as rw). When x86 > doesn't support HW boost - DO NOT export it at all. > > At v4: > 1. ARM - export "boost" only when supported (rw) > 2. x86 - always export boost - no matter if supported or not. If not > supported, then export it as ro only. Okay, there is some confusion.. I have raised a query on your v4 mail.. lets see what people have to say. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v5 7/7] Documentation:cpufreq:boost: Update BOOST documentation
On Wed, 17 Jul 2013 10:52:18 +0530 Viresh Kumar viresh.ku...@linaro.org wrote, > On 16 July 2013 17:03, Lukasz Majewski wrote: > > As fair as I've understood our previous discussion (at [*]) we have > > agreed about this. We only export boost attribute when it is > > supported by cpufreq_driver. Rafael was very clear about exporting > > boost attribute: > > > > "Simple: Export it only when supported." > > > > [*]: Re: [PATCH v4 2/7] cpufreq: Add boost frequency support in core > > I don't want to search in the Archives but I am sure what we decided > earlier. At v4 there was the old acpi-cpufreq.c behaviour preserved (with always exporting boost - when not supported ro, when supported rw). Due to Rafael and Dirk comments it has been rewritten at v5: http://thread.gmane.org/gmane.linux.kernel/1511831/match=patch+v4+2+7+cpufreq+add+boost+frequency+support+core > > Rafael Said: > "Simple: Export it only when supported." [*] > > AND > > "Don't change behavior of acpi-cpufreq driver" [**] > > If you see acpi-cpufreq driver carefully, it always creates "boost" > sysfs entry. If its not supported then it creates a read only entry. For me those two statements [*] and [**] contradict: At v5: 1. ARM - export "boost" only when supported (rw) 2. x86 - export boost only when x86 supports it (as rw). When x86 doesn't support HW boost - DO NOT export it at all. At v4: 1. ARM - export "boost" only when supported (rw) 2. x86 - always export boost - no matter if supported or not. If not supported, then export it as ro only. > > So, please preserve that. -- Best regards, Lukasz Majewski Samsung R&D Institute Poland (SRPOL) | Linux Platform Group -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v5 7/7] Documentation:cpufreq:boost: Update BOOST documentation
On 16 July 2013 17:03, Lukasz Majewski wrote: > As fair as I've understood our previous discussion (at [*]) we have > agreed about this. We only export boost attribute when it is supported > by cpufreq_driver. Rafael was very clear about exporting boost > attribute: > > "Simple: Export it only when supported." > > [*]: Re: [PATCH v4 2/7] cpufreq: Add boost frequency support in core I don't want to search in the Archives but I am sure what we decided earlier. Rafael Said: "Simple: Export it only when supported." AND "Don't change behavior of acpi-cpufreq driver" If you see acpi-cpufreq driver carefully, it always creates "boost" sysfs entry. If its not supported then it creates a read only entry. So, please preserve that. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v5 7/7] Documentation:cpufreq:boost: Update BOOST documentation
On Tue, 16 Jul 2013 15:31:43 +0530 Viresh Kumar viresh.ku...@linaro.org wrote, > On 4 July 2013 14:20, Lukasz Majewski wrote: > > -Reading the file is always supported, even if the processor does > > not -support boosting. In this case the file will be read-only and > > always -reads as "0". Explicitly changing the permissions and > > writing to that -file anyway will return EINVAL. > > +The file is exported only when cpufreq driver supports boosting. > > +Explicitly changing the permissions and writing to that file > > anyway will +return EINVAL. > > For acpi-cpufreq reading the file should be always supported. And this > must be mentioned in doc. As fair as I've understood our previous discussion (at [*]) we have agreed about this. We only export boost attribute when it is supported by cpufreq_driver. Rafael was very clear about exporting boost attribute: "Simple: Export it only when supported." [*]: Re: [PATCH v4 2/7] cpufreq: Add boost frequency support in core -- Best regards, Lukasz Majewski Samsung R&D Institute Poland (SRPOL) | Linux Platform Group -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v5 7/7] Documentation:cpufreq:boost: Update BOOST documentation
On 4 July 2013 14:20, Lukasz Majewski wrote: > -Reading the file is always supported, even if the processor does not > -support boosting. In this case the file will be read-only and always > -reads as "0". Explicitly changing the permissions and writing to that > -file anyway will return EINVAL. > +The file is exported only when cpufreq driver supports boosting. > +Explicitly changing the permissions and writing to that file anyway will > +return EINVAL. For acpi-cpufreq reading the file should be always supported. And this must be mentioned in doc. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH v5 7/7] Documentation:cpufreq:boost: Update BOOST documentation
Since the support for software and hardware controlled boosting has been added, the corresponding Documentation entry had been updated. Signed-off-by: Lukasz Majewski Signed-off-by: Myungjoo Ham --- Changes for v5: - New patch Documentation/cpu-freq/boost.txt | 26 +- 1 file changed, 13 insertions(+), 13 deletions(-) diff --git a/Documentation/cpu-freq/boost.txt b/Documentation/cpu-freq/boost.txt index 9b4edfc..dd62e13 100644 --- a/Documentation/cpu-freq/boost.txt +++ b/Documentation/cpu-freq/boost.txt @@ -17,8 +17,8 @@ Introduction Some CPUs support a functionality to raise the operating frequency of some cores in a multi-core package if certain conditions apply, mostly if the whole chip is not fully utilized and below it's intended thermal -budget. This is done without operating system control by a combination -of hardware and firmware. +budget. The decision about boost disable/enable is made either at hardware +(e.g. x86) or software (e.g ARM). On Intel CPUs this is called "Turbo Boost", AMD calls it "Turbo-Core", in technical documentation "Core performance boost". In Linux we use the term "boost" for convenience. @@ -48,24 +48,24 @@ be desirable: User controlled switch -- -To allow the user to toggle the boosting functionality, the acpi-cpufreq -driver exports a sysfs knob to disable it. There is a file: +To allow the user to toggle the boosting functionality, the cpufreq core +driver exports a sysfs knob to enable or disable it. There is a file: /sys/devices/system/cpu/cpufreq/boost which can either read "0" (boosting disabled) or "1" (boosting enabled). -Reading the file is always supported, even if the processor does not -support boosting. In this case the file will be read-only and always -reads as "0". Explicitly changing the permissions and writing to that -file anyway will return EINVAL. +The file is exported only when cpufreq driver supports boosting. +Explicitly changing the permissions and writing to that file anyway will +return EINVAL. On supported CPUs one can write either a "0" or a "1" into this file. This will either disable the boost functionality on all cores in the -whole system (0) or will allow the hardware to boost at will (1). +whole system (0) or will allow the software or hardware to boost at will +(1). Writing a "1" does not explicitly boost the system, but just allows the -CPU (and the firmware) to boost at their discretion. Some implementations -take external factors like the chip's temperature into account, so -boosting once does not necessarily mean that it will occur every time -even using the exact same software setup. +CPU to boost at their discretion. Some implementations take external +factors like the chip's temperature into account, so boosting once does +not necessarily mean that it will occur every time even using the exact +same software setup. AMD legacy cpb switch -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/