On 11/15/24 03:43, Alex Bennée wrote:
> Pierrick Bouvier <pierrick.bouvier@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~
>