From 9204384f84e8a05e05dc4f61cacad548d3cf827c Mon Sep 17 00:00:00 2001 From: James Hughes Date: Wed, 27 Nov 2019 11:41:28 +0000 Subject: [PATCH 1/9] Update frequency-management.md --- hardware/raspberrypi/frequency-management.md | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/hardware/raspberrypi/frequency-management.md b/hardware/raspberrypi/frequency-management.md index 61ad62ceb..dd18ed7ad 100644 --- a/hardware/raspberrypi/frequency-management.md +++ b/hardware/raspberrypi/frequency-management.md @@ -8,6 +8,14 @@ For Raspberry Pi 3 Model B+, the PCB technology has been changed to provide bett The Raspberry Pi 4 Model B continues with the same PCB technology as the Raspberry Pi 3B+ to help dissipate excess heat. There is currently no soft limit defined. +### DVFS on the Raspberry Pi 4 + +On the Raspberry Pi 4, firmware from late November 2019 onwards implements Dynamic Voltage and Frequency Scaling. This technique (outlined on Wikipedia [here](https://en.wikipedia.org/wiki/Dynamic_voltage_scaling)) allows the Pi4 to run at lower temperatures whilst still providing the same performance. + +Various clocks (e.g. ARM, Core, v3d, ISP, H264, HEVC) inside the SoC are monitored by the firmware, and whenever they are not running at full speed, the voltage supplied to the particular part of the chip driven by the clock is reduced relative to the reduction from full speed. In effect, only enough voltage is supplied to keep the block running correctly at the specific speed it is running at. This can result in significant reductions in power used by the SoC, and therefor the overall heat being produced. + +in addition, a more stepped CPU governor is also used to produced more fine grained control of ARM core frequencies which means the DVFS is more effective. The steps are now 1500, 1000, 750, and 600. These steps can also help under throttling conditions, and mean that throttling all the way back to 600 is much less likely, giving an overalll increase in fully loaded performance. + ### Heatsinks Whilst heatsinks are not necessary to prevent overheating damage to the SoC (the thermal throttling mechanism handles that), a heatsink or small fan will help if you wish to reduce the amount of thermal throttling that takes place. Depending on the exact circumstances, mounting the Pi vertically can also help with heat dissipation, as doing so can improve air flow. From 886607cdad8c6af93256e162b26625aa3e72b6a9 Mon Sep 17 00:00:00 2001 From: Andrew Scheller Date: Mon, 2 Dec 2019 10:28:12 +0000 Subject: [PATCH 2/9] fix minor typos --- hardware/raspberrypi/frequency-management.md | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/hardware/raspberrypi/frequency-management.md b/hardware/raspberrypi/frequency-management.md index dd18ed7ad..acc6c943a 100644 --- a/hardware/raspberrypi/frequency-management.md +++ b/hardware/raspberrypi/frequency-management.md @@ -12,9 +12,9 @@ The Raspberry Pi 4 Model B continues with the same PCB technology as the Raspber On the Raspberry Pi 4, firmware from late November 2019 onwards implements Dynamic Voltage and Frequency Scaling. This technique (outlined on Wikipedia [here](https://en.wikipedia.org/wiki/Dynamic_voltage_scaling)) allows the Pi4 to run at lower temperatures whilst still providing the same performance. -Various clocks (e.g. ARM, Core, v3d, ISP, H264, HEVC) inside the SoC are monitored by the firmware, and whenever they are not running at full speed, the voltage supplied to the particular part of the chip driven by the clock is reduced relative to the reduction from full speed. In effect, only enough voltage is supplied to keep the block running correctly at the specific speed it is running at. This can result in significant reductions in power used by the SoC, and therefor the overall heat being produced. +Various clocks (e.g. ARM, Core, v3d, ISP, H264, HEVC) inside the SoC are monitored by the firmware, and whenever they are not running at full speed, the voltage supplied to the particular part of the chip driven by the clock is reduced relative to the reduction from full speed. In effect, only enough voltage is supplied to keep the block running correctly at the specific speed it is running at. This can result in significant reductions in power used by the SoC, and therefore the overall heat being produced. -in addition, a more stepped CPU governor is also used to produced more fine grained control of ARM core frequencies which means the DVFS is more effective. The steps are now 1500, 1000, 750, and 600. These steps can also help under throttling conditions, and mean that throttling all the way back to 600 is much less likely, giving an overalll increase in fully loaded performance. +In addition, a more stepped CPU governor is also used to produce more fine grained control of ARM core frequencies which means the DVFS is more effective. The steps are now 1500, 1000, 750, and 600. These steps can also help under throttling conditions, and mean that throttling all the way back to 600 is much less likely, giving an overalll increase in fully loaded performance. ### Heatsinks From b65b820a6a27623525b5dd8a7cce11d2cca5d2ad Mon Sep 17 00:00:00 2001 From: James Hughes Date: Mon, 2 Dec 2019 15:26:54 +0000 Subject: [PATCH 3/9] Update frequency-management.md --- hardware/raspberrypi/frequency-management.md | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/hardware/raspberrypi/frequency-management.md b/hardware/raspberrypi/frequency-management.md index acc6c943a..2a5a634be 100644 --- a/hardware/raspberrypi/frequency-management.md +++ b/hardware/raspberrypi/frequency-management.md @@ -10,11 +10,11 @@ The Raspberry Pi 4 Model B continues with the same PCB technology as the Raspber ### DVFS on the Raspberry Pi 4 -On the Raspberry Pi 4, firmware from late November 2019 onwards implements Dynamic Voltage and Frequency Scaling. This technique (outlined on Wikipedia [here](https://en.wikipedia.org/wiki/Dynamic_voltage_scaling)) allows the Pi4 to run at lower temperatures whilst still providing the same performance. +On the Raspberry Pi 4B, firmware from late November 2019 onwards implements Dynamic Voltage and Frequency Scaling. This technique (outlined on Wikipedia [here](https://en.wikipedia.org/wiki/Dynamic_voltage_scaling)) allows the Pi4 to run at lower temperatures whilst still providing the same performance. Various clocks (e.g. ARM, Core, v3d, ISP, H264, HEVC) inside the SoC are monitored by the firmware, and whenever they are not running at full speed, the voltage supplied to the particular part of the chip driven by the clock is reduced relative to the reduction from full speed. In effect, only enough voltage is supplied to keep the block running correctly at the specific speed it is running at. This can result in significant reductions in power used by the SoC, and therefore the overall heat being produced. -In addition, a more stepped CPU governor is also used to produce more fine grained control of ARM core frequencies which means the DVFS is more effective. The steps are now 1500, 1000, 750, and 600. These steps can also help under throttling conditions, and mean that throttling all the way back to 600 is much less likely, giving an overalll increase in fully loaded performance. +In addition, a more stepped CPU governor is also used to produce more fine grained control of ARM core frequencies which means the DVFS is more effective. The steps are now 1500, 1000, 750, and 600. These steps can also help when the SoC is being throttled, and mean that throttling all the way back to 600 is much less likely, giving an overall increase in fully loaded performance. ### Heatsinks From a573a70b1d6a9528acafcb013c653a405ebe16a0 Mon Sep 17 00:00:00 2001 From: James Hughes Date: Mon, 2 Dec 2019 15:27:39 +0000 Subject: [PATCH 4/9] Update frequency-management.md --- hardware/raspberrypi/frequency-management.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/hardware/raspberrypi/frequency-management.md b/hardware/raspberrypi/frequency-management.md index 2a5a634be..fd656ec8c 100644 --- a/hardware/raspberrypi/frequency-management.md +++ b/hardware/raspberrypi/frequency-management.md @@ -12,7 +12,7 @@ The Raspberry Pi 4 Model B continues with the same PCB technology as the Raspber On the Raspberry Pi 4B, firmware from late November 2019 onwards implements Dynamic Voltage and Frequency Scaling. This technique (outlined on Wikipedia [here](https://en.wikipedia.org/wiki/Dynamic_voltage_scaling)) allows the Pi4 to run at lower temperatures whilst still providing the same performance. -Various clocks (e.g. ARM, Core, v3d, ISP, H264, HEVC) inside the SoC are monitored by the firmware, and whenever they are not running at full speed, the voltage supplied to the particular part of the chip driven by the clock is reduced relative to the reduction from full speed. In effect, only enough voltage is supplied to keep the block running correctly at the specific speed it is running at. This can result in significant reductions in power used by the SoC, and therefore the overall heat being produced. +Various clocks (e.g. ARM, Core, V3D, ISP, H264, HEVC) inside the SoC are monitored by the firmware, and whenever they are not running at full speed, the voltage supplied to the particular part of the chip driven by the clock is reduced relative to the reduction from full speed. In effect, only enough voltage is supplied to keep the block running correctly at the specific speed it is running at. This can result in significant reductions in power used by the SoC, and therefore the overall heat being produced. In addition, a more stepped CPU governor is also used to produce more fine grained control of ARM core frequencies which means the DVFS is more effective. The steps are now 1500, 1000, 750, and 600. These steps can also help when the SoC is being throttled, and mean that throttling all the way back to 600 is much less likely, giving an overall increase in fully loaded performance. From d470c592308767f0f8b4515b22f87a9bee601251 Mon Sep 17 00:00:00 2001 From: Andrew Scheller Date: Mon, 2 Dec 2019 15:54:32 +0000 Subject: [PATCH 5/9] minor edits --- hardware/raspberrypi/frequency-management.md | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/hardware/raspberrypi/frequency-management.md b/hardware/raspberrypi/frequency-management.md index fd656ec8c..1c3d2a246 100644 --- a/hardware/raspberrypi/frequency-management.md +++ b/hardware/raspberrypi/frequency-management.md @@ -8,13 +8,13 @@ For Raspberry Pi 3 Model B+, the PCB technology has been changed to provide bett The Raspberry Pi 4 Model B continues with the same PCB technology as the Raspberry Pi 3B+ to help dissipate excess heat. There is currently no soft limit defined. -### DVFS on the Raspberry Pi 4 +### DVFS on the Raspberry Pi 4B -On the Raspberry Pi 4B, firmware from late November 2019 onwards implements Dynamic Voltage and Frequency Scaling. This technique (outlined on Wikipedia [here](https://en.wikipedia.org/wiki/Dynamic_voltage_scaling)) allows the Pi4 to run at lower temperatures whilst still providing the same performance. +On the Raspberry Pi 4B, firmware from late November 2019 onwards implements Dynamic Voltage and Frequency Scaling. This technique (outlined on Wikipedia [here](https://en.wikipedia.org/wiki/Dynamic_voltage_scaling)) allows the Raspberry Pi 4B to run at lower temperatures whilst still providing the same performance. Various clocks (e.g. ARM, Core, V3D, ISP, H264, HEVC) inside the SoC are monitored by the firmware, and whenever they are not running at full speed, the voltage supplied to the particular part of the chip driven by the clock is reduced relative to the reduction from full speed. In effect, only enough voltage is supplied to keep the block running correctly at the specific speed it is running at. This can result in significant reductions in power used by the SoC, and therefore the overall heat being produced. -In addition, a more stepped CPU governor is also used to produce more fine grained control of ARM core frequencies which means the DVFS is more effective. The steps are now 1500, 1000, 750, and 600. These steps can also help when the SoC is being throttled, and mean that throttling all the way back to 600 is much less likely, giving an overall increase in fully loaded performance. +In addition, a more stepped CPU governor is also used to produce more fine-grained control of ARM core frequencies, which means the DVFS is more effective. The steps are now 1500, 1000, 750, and 600. These steps can also help when the SoC is being throttled, and mean that throttling all the way back to 600 is much less likely, giving an overall increase in fully loaded performance. ### Heatsinks From 11544aebfca770ea7bf0b682ef71c00162f2924e Mon Sep 17 00:00:00 2001 From: James Hughes Date: Mon, 2 Dec 2019 16:49:38 +0000 Subject: [PATCH 6/9] Update frequency-management.md --- hardware/raspberrypi/frequency-management.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/hardware/raspberrypi/frequency-management.md b/hardware/raspberrypi/frequency-management.md index 1c3d2a246..aade47ad0 100644 --- a/hardware/raspberrypi/frequency-management.md +++ b/hardware/raspberrypi/frequency-management.md @@ -14,7 +14,7 @@ On the Raspberry Pi 4B, firmware from late November 2019 onwards implements Dyna Various clocks (e.g. ARM, Core, V3D, ISP, H264, HEVC) inside the SoC are monitored by the firmware, and whenever they are not running at full speed, the voltage supplied to the particular part of the chip driven by the clock is reduced relative to the reduction from full speed. In effect, only enough voltage is supplied to keep the block running correctly at the specific speed it is running at. This can result in significant reductions in power used by the SoC, and therefore the overall heat being produced. -In addition, a more stepped CPU governor is also used to produce more fine-grained control of ARM core frequencies, which means the DVFS is more effective. The steps are now 1500, 1000, 750, and 600. These steps can also help when the SoC is being throttled, and mean that throttling all the way back to 600 is much less likely, giving an overall increase in fully loaded performance. +In addition, a more stepped CPU governor is also used to produce finer-grained control of ARM core frequencies, which means the DVFS is more effective. The steps are now 1500MHz, 1000MHz, 750MHz, and 600MHz. These steps can also help when the SoC is being throttled, and mean that throttling all the way back to 600MHz is much less likely, giving an overall increase in fully loaded performance. ### Heatsinks From 4c1e4f36e5dcd0560442bc1084ee17a00b813563 Mon Sep 17 00:00:00 2001 From: Andrew Scheller Date: Mon, 2 Dec 2019 17:54:54 +0000 Subject: [PATCH 7/9] add degree symbol --- hardware/raspberrypi/frequency-management.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/hardware/raspberrypi/frequency-management.md b/hardware/raspberrypi/frequency-management.md index aade47ad0..89c41e7d0 100644 --- a/hardware/raspberrypi/frequency-management.md +++ b/hardware/raspberrypi/frequency-management.md @@ -4,7 +4,7 @@ All Raspberry Pi models perform a degree of thermal management to avoid overheat With firmware from 12 September 2016 or later, when the core temperature is between 80°C and 85°C, a warning icon showing a red half-filled thermometer will be displayed, and the ARM cores will be progressively throttled back. If the temperature reaches 85°C, an icon showing a fully-filled thermometer will be displayed, and both the ARM cores and the GPU will be throttled back. See the page on [warning icons](../../configuration/warning-icons.md) for images of the icons. -For Raspberry Pi 3 Model B+, the PCB technology has been changed to provide better heat dissipation and increased thermal mass. In addition, a soft temperature limit has been introduced, with the goal of maximising the time for which a device can "sprint" before reaching the hard limit at 85'C. When the soft limit is reached, the clock speed is reduced from 1.4GHz to 1.2GHz, and the operating voltage is reduced slightly. This reduces the rate of temperature increase: we trade a short period at 1.4GHz for a longer period at 1.2GHz. By default, the soft limit is 60°C, and this can be changed via the `temp_soft_limit` setting in [config.txt](../../configuration/config-txt/overclocking.md). +For Raspberry Pi 3 Model B+, the PCB technology has been changed to provide better heat dissipation and increased thermal mass. In addition, a soft temperature limit has been introduced, with the goal of maximising the time for which a device can "sprint" before reaching the hard limit at 85°C. When the soft limit is reached, the clock speed is reduced from 1.4GHz to 1.2GHz, and the operating voltage is reduced slightly. This reduces the rate of temperature increase: we trade a short period at 1.4GHz for a longer period at 1.2GHz. By default, the soft limit is 60°C, and this can be changed via the `temp_soft_limit` setting in [config.txt](../../configuration/config-txt/overclocking.md). The Raspberry Pi 4 Model B continues with the same PCB technology as the Raspberry Pi 3B+ to help dissipate excess heat. There is currently no soft limit defined. From bbbdfaaaba704208d4a98bda5bf2963f79d4535e Mon Sep 17 00:00:00 2001 From: James Hughes Date: Mon, 9 Dec 2019 10:02:02 +0000 Subject: [PATCH 8/9] Update frequency-management.md --- hardware/raspberrypi/frequency-management.md | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/hardware/raspberrypi/frequency-management.md b/hardware/raspberrypi/frequency-management.md index 89c41e7d0..0318a871f 100644 --- a/hardware/raspberrypi/frequency-management.md +++ b/hardware/raspberrypi/frequency-management.md @@ -2,7 +2,7 @@ All Raspberry Pi models perform a degree of thermal management to avoid overheating under heavy load. The SoCs have an internal temperature sensor, which software on the GPU polls to ensure that temperatures do not exceed a predefined limit; this is 85°C on all models. It is possible to set this to a lower value, but not to a higher one. As the device approaches the limit, various frequencies and sometimes voltages used on the chip (ARM, GPU) are reduced. This reduces the amount of heat generated, keeping the temperature under control. -With firmware from 12 September 2016 or later, when the core temperature is between 80°C and 85°C, a warning icon showing a red half-filled thermometer will be displayed, and the ARM cores will be progressively throttled back. If the temperature reaches 85°C, an icon showing a fully-filled thermometer will be displayed, and both the ARM cores and the GPU will be throttled back. See the page on [warning icons](../../configuration/warning-icons.md) for images of the icons. +When the core temperature is between 80°C and 85°C, a warning icon showing a red half-filled thermometer will be displayed, and the ARM cores will be progressively throttled back. If the temperature reaches 85°C, an icon showing a fully-filled thermometer will be displayed, and both the ARM cores and the GPU will be throttled back. See the page on [warning icons](../../configuration/warning-icons.md) for images of the icons. For Raspberry Pi 3 Model B+, the PCB technology has been changed to provide better heat dissipation and increased thermal mass. In addition, a soft temperature limit has been introduced, with the goal of maximising the time for which a device can "sprint" before reaching the hard limit at 85°C. When the soft limit is reached, the clock speed is reduced from 1.4GHz to 1.2GHz, and the operating voltage is reduced slightly. This reduces the rate of temperature increase: we trade a short period at 1.4GHz for a longer period at 1.2GHz. By default, the soft limit is 60°C, and this can be changed via the `temp_soft_limit` setting in [config.txt](../../configuration/config-txt/overclocking.md). @@ -22,6 +22,6 @@ Whilst heatsinks are not necessary to prevent overheating damage to the SoC (the ### Measuring temperature -Due to the architecture of the SoCs used on the Raspberry Pi range, and the use of the upstream temperature monitoring code in the Raspbian distribtution, Linux-based temperature measurements can be inaccurate. There is a `gencmd` that can provide an accurate and instantaneous reading of the current SoC temperature, as it communicates with the GPU directly: +Due to the architecture of the SoCs used on the Raspberry Pi range, and the use of the upstream temperature monitoring code in the Raspbian distribtution, Linux-based temperature measurements can be inaccurate. There is a command that can provide an accurate and instantaneous reading of the current SoC temperature, as it communicates with the GPU directly: ```vcgencmd measure_temp``` From 94295bee6ef64a6997824e6ffb7c7a929b527915 Mon Sep 17 00:00:00 2001 From: James Hughes Date: Mon, 9 Dec 2019 16:18:43 +0000 Subject: [PATCH 9/9] Update frequency-management.md --- hardware/raspberrypi/frequency-management.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/hardware/raspberrypi/frequency-management.md b/hardware/raspberrypi/frequency-management.md index 0318a871f..d6bb6d4ed 100644 --- a/hardware/raspberrypi/frequency-management.md +++ b/hardware/raspberrypi/frequency-management.md @@ -22,6 +22,6 @@ Whilst heatsinks are not necessary to prevent overheating damage to the SoC (the ### Measuring temperature -Due to the architecture of the SoCs used on the Raspberry Pi range, and the use of the upstream temperature monitoring code in the Raspbian distribtution, Linux-based temperature measurements can be inaccurate. There is a command that can provide an accurate and instantaneous reading of the current SoC temperature, as it communicates with the GPU directly: +Due to the architecture of the SoCs used on the Raspberry Pi range, and the use of the upstream temperature monitoring code in the Raspbian distribution, Linux-based temperature measurements can be inaccurate. There is a command that can provide an accurate and instantaneous reading of the current SoC temperature, as it communicates with the GPU directly: ```vcgencmd measure_temp```