On 11/15/24 03:43, Alex Bennée wrote:
Pierrick Bouvier <pierrick.bouv...@linaro.org> writes:
On 11/14/24 12:58, Richard Henderson wrote:
On 11/14/24 11:56, Pierrick Bouvier wrote:
I tested this change by booting a debian x86_64 image, it works as expected.
I noticed that this change does not come for free (64s before, 82s after -
1.3x). Is that
acceptable?
Well, no. But I didn't notice any change during boot tests. I used hyperfine
over 'make
check-functional'.
I would only expect benefits to be seen during longer lived vm's,
since a boot test
doesn't run applications long enough to see tlb entries accumulate. I have not
attempted
to create a reproducible test for that so far.
I didn't use check-functional neither.
I used a vanilla debian bookworm install, with a modified
/etc/rc.local calling poweroff, and ran 3 times with/without change
with turbo disabled on my cpu.
If you want to really stress the VM handling you should use stress-ng to
exercise page faulting and recovery. Wrap it up in a systemd unit for a
reproducible test:
cat /etc/systemd/system/benchmark-stress-ng.service
# A benchmark target
#
# This shutsdown once the boot has completed
[Unit]
Description=Default
Requires=basic.target
After=basic.target
AllowIsolate=yes
[Service]
Type=oneshot
ExecStart=stress-ng --perf --iomix 4 --vm 2 --timeout 10s
ExecStartPost=/sbin/poweroff
[Install]
WantedBy=multi-user.target
and then call with something like:
-append "root=/dev/sda2 console=ttyAMA0
systemd.unit=benchmark-stress-ng.service"
Thanks for the advice.
r~
