[Vm-dev] ulimit rat-rio setting (was Re: [OpenSmalltalk/opensmalltalk-vm] Do not use linux-latest runner, use an older stable version. (#598))

[Eliot Miranda]

> On Sep 29, 2021, at 5:32 PM, David T. Lewis <lewis at mail.msen.com> wrote:
> 
> 
>> On Tue, Sep 28, 2021 at 03:12:29PM -0700, tim Rowledge wrote:
>> 
>> This reminds me to ask (probably again) if anyone actually understands
>> ubuntu and getting the rtprio settings to 'take'.
>> 
>> I have the suggested /etc/security/limits.d/squeak.conf etc but it
>> appears to be ignored - at least the VM complains about it. Since
>> `ulimit -a` tells me that rtprio is 0, I suspect it is correct to
>> complain. I've spent way too long trying to make sense of what I
>> find with googling. This has been going on for ages (so, yes, the
>> machine has been rebooted) and every now and then I try to make some
>> sense of it. 
>> 
> 
> Aside from the various discussions of how to work around this problem,
> I would expect that the VM might better do something like this:
> 
> - Attempt to start the heartbeat thread at elevated priority.
> - If successful, proceed as before (other threads at normal priority)
> - If not successful, drop the process priority and start all other
>  threads at a lower priority.

+1.  Good idea!

> 
> Note that running at lower priority does not affect performance or
> user experience for most users. You can verify this yourself by running
> Squeak at lower priority using the "nice" command, and see if you can
> notice any difference.
> 
> I have not looked at how to implement the above, but my expectation
> is that the strategy would give good results for most users, while
> eliminating the need for root access for first-time users installing
> Squeak.
> 
> Dave
>