On 11/7/22 10:18, Khem Raj wrote:
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On Sun, Nov 6, 2022 at 5:21 PM Xiangyu Chen <[email protected]> wrote:
On 11/1/22 09:48, Xiangyu Chen wrote:
With the default jitter options aarch64 CPU-based devices typically experience
continuous
high CPU utilisation for several minutes after rngd starts.
Accoring to the rng-tools issue #150[1] and comments[2],in order to address
this,
the following configuration changes have been made, those configurations
also can be found on Alpine Linux[3]:
- reduce the number of threads used to 1 in total, rather than 1 per core.
- reduce the buffer size from 16535 to 4133 which reduces the time taken
to fill the buffer (and so reduces the duration of CPU load).
[1] https://github.com/nhorman/rng-tools/issues/150
[2] https://github.com/nhorman/rng-tools/issues/150#issuecomment-953079212
[3] https://git.alpinelinux.org/aports/tree/main/rng-tools/rngd.confd-arm
Signed-off-by: Xiangyu Chen <[email protected]>
---
Changes in V2:
*put the aarch64 specific default file in
meta/recipes-support/rng-tools/rng-tools/aarch64
Friendly ping. Is there any more concern on this?
My concern is that will it be so for all aarch64 machines ?
Regarding the rng-tools high cpu usage still need to be discussed here.
Currently, on some platforms like ARM, there is not any good idea to
solve the rng-tools jitter module take full cpu load during the daemon
start. In fact, after kernel v5.6, the /dev/random doesn't block
anymore, so, perhaps we can use the parameter to limit rng-tools
resource during it start up, does anyone have any ideas to propose? Thanks!
Br,
Xiangyu
Thanks,
Xiangyu
---
.../rng-tools/rng-tools/aarch64/default | 11 +++++++++++
1 file changed, 11 insertions(+)
create mode 100644 meta/recipes-support/rng-tools/rng-tools/aarch64/default
diff --git a/meta/recipes-support/rng-tools/rng-tools/aarch64/default
b/meta/recipes-support/rng-tools/rng-tools/aarch64/default
new file mode 100644
index 0000000000..5a2fbcc9ef
--- /dev/null
+++ b/meta/recipes-support/rng-tools/rng-tools/aarch64/default
@@ -0,0 +1,11 @@
+# With the default jitter options Arm CPU-based devices typically experience
+# continuous high CPU utilisation for several minutes after rngd starts.
+# See https://gitlab.alpinelinux.org/alpine/aports/-/issues/13035 and
+# https://github.com/nhorman/rng-tools/issues/150
+# In order to address this the following configuration changes have been made:
+#
+# - reduce the number of threads used to 1 in total, rather than 1 per core.
+# - reduce the buffer size from 16535 to 4133 which reduces the time taken
+# to fill the buffer (and so reduces the duration of CPU load).
+#
+EXTRA_ARGS="-r /dev/hwrng -O jitter:buffer_size:4133 -O jitter:refill_thresh:4133
-O jitter:thread_count:1"
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