diff --git a/source/devices/AM62AX/linux/RT_Linux_Performance_Guide.rst b/source/devices/AM62AX/linux/RT_Linux_Performance_Guide.rst index 44eb553f7..798f6c233 100644 --- a/source/devices/AM62AX/linux/RT_Linux_Performance_Guide.rst +++ b/source/devices/AM62AX/linux/RT_Linux_Performance_Guide.rst @@ -62,13 +62,17 @@ default SDK image: .. note:: - A known issue in this SDK release is affecting this benchmark. - Using OP-TEEs PRNG drivers rather than the hardware accelerated - TRNG drivers restores the context switch latencies to the values you - see here. - - More information on switching to the PRNG drivers can be found in the - Foundational Components section, here :ref:`building-optee-with-prng` + Using the OP-TEE TRNG driver can impact this benchmark's performance due to + frequent context switching between Normal World (Linux) and Secure World (OP-TEE), + that occurs when the kernel's hardware random number generator interface + (hwrng) requests entropy from the secure TRNG to replenish the Linux entropy + pool. + + The Linux TRNG driver can mitigate these latency spikes. This involves + enabling the Pseudo RNG driver in OP-TEE as documented in the Foundational + Components section: :ref:`building-optee-with-prng`, and enabling the RNG + node in the Linux kernel device tree. This way the HW TRNG is accessed from + the kernel itself. .. csv-table:: :header: "Latencies","CPU 0","CPU 1","CPU 2","CPU 3" diff --git a/source/devices/AM62LX/linux/RT_Linux_Performance_Guide.rst b/source/devices/AM62LX/linux/RT_Linux_Performance_Guide.rst index ab01f01af..cb13d850b 100644 --- a/source/devices/AM62LX/linux/RT_Linux_Performance_Guide.rst +++ b/source/devices/AM62LX/linux/RT_Linux_Performance_Guide.rst @@ -61,13 +61,17 @@ default SDK image: .. note:: - A known issue in this SDK release is affecting this benchmark. - Using OP-TEEs PRNG drivers rather than the hardware accelerated TRNG - drivers restores the context switch latencies to the values you see - here. - - More information on switching to the PRNG drivers can be found in the - Foundational Components section, here :ref:`building-optee-with-prng` + Using the OP-TEE TRNG driver can impact this benchmark's performance due to + frequent context switching between Normal World (Linux) and Secure World (OP-TEE), + that occurs when the kernel's hardware random number generator interface + (hwrng) requests entropy from the secure TRNG to replenish the Linux entropy + pool. + + The Linux TRNG driver can mitigate these latency spikes. This involves + enabling the Pseudo RNG driver in OP-TEE as documented in the Foundational + Components section: :ref:`building-optee-with-prng`, and enabling the RNG + node in the Linux kernel device tree. This way the HW TRNG is accessed from + the kernel itself. .. csv-table:: :header: "Latencies","CPU 0","CPU 1" diff --git a/source/devices/AM62PX/linux/RT_Linux_Performance_Guide.rst b/source/devices/AM62PX/linux/RT_Linux_Performance_Guide.rst index d02ecea29..6d68d7b90 100644 --- a/source/devices/AM62PX/linux/RT_Linux_Performance_Guide.rst +++ b/source/devices/AM62PX/linux/RT_Linux_Performance_Guide.rst @@ -62,13 +62,17 @@ default SDK image .. note:: - A known issue in this SDK release is affecting this benchmark. - Using OP-TEEs PRNG drivers rather than the hardware accelerated TRNG - drivers restores the context switch latencies to the values you see - here. - - More information on switching to the PRNG drivers can be found in the - Foundational Components section, here :ref:`building-optee-with-prng` + Using the OP-TEE TRNG driver can impact this benchmark's performance due to + frequent context switching between Normal World (Linux) and Secure World (OP-TEE), + that occurs when the kernel's hardware random number generator interface + (hwrng) requests entropy from the secure TRNG to replenish the Linux entropy + pool. + + The Linux TRNG driver can mitigate these latency spikes. This involves + enabling the Pseudo RNG driver in OP-TEE as documented in the Foundational + Components section: :ref:`building-optee-with-prng`, and enabling the RNG + node in the Linux kernel device tree. This way the HW TRNG is accessed from + the kernel itself. .. csv-table:: :header: "Latencies","CPU 0","CPU 1","CPU 2","CPU 3" diff --git a/source/devices/AM62X/linux/RT_Linux_Performance_Guide.rst b/source/devices/AM62X/linux/RT_Linux_Performance_Guide.rst index e835e18f1..ddc4099f2 100644 --- a/source/devices/AM62X/linux/RT_Linux_Performance_Guide.rst +++ b/source/devices/AM62X/linux/RT_Linux_Performance_Guide.rst @@ -68,13 +68,17 @@ default SDK image using the SK-AM62B-P1_ reference board: .. note:: - A known issue in this SDK release is affecting this benchmark. - Using OP-TEE's PRNG drivers rather than the hardware accelerated TRNG - drivers restores the context switch latencies to the values you see - here. - - More information on switching to the PRNG drivers can be found in the - Foundational Components section, here :ref:`building-optee-with-prng` + Using the OP-TEE TRNG driver can impact this benchmark's performance due to + frequent context switching between Normal World (Linux) and Secure World (OP-TEE), + that occurs when the kernel's hardware random number generator interface + (hwrng) requests entropy from the secure TRNG to replenish the Linux entropy + pool. + + The Linux TRNG driver can mitigate these latency spikes. This involves + enabling the Pseudo RNG driver in OP-TEE as documented in the Foundational + Components section: :ref:`building-optee-with-prng`, and enabling the RNG + node in the Linux kernel device tree. This way the HW TRNG is accessed from + the kernel itself. .. csv-table:: :header: "Latencies","CPU 0","CPU 1","CPU 2","CPU 3"