+1
There are several applications ( high throughput, simple control
systems ) where isolcpus is used as a simple way to extract maximum
performance.
Request the team to please consult more widely before removing isolcpu.
Please let us know if a different venue/mailing list is the best site
for feedback regarding this topic.
Best
Gautham
On Thu, 28 Sept 2023 at 15:20, Rod Webster <rod@xxxxxxxxxx> wrote:
>
> We in the linuxCNC community would not be in favour of removing isolcpus.
> In our application there are only one or sometimes two RT threads, a
> large user base deployed on a variety of platforms.
> isolcpus gives our users a simple way to optionally improve RT performance.
> When I review the cpusets documentation, it adds additional complexity
> to configuration.
> Our users are machinists, not IT professionals so would likely
> struggle to configure a cpusets environment.
> The LinuxCNC application is deployed on machine controllers so boot
> time parameters are not an issue and likely preferred.
>
> It would be appreciated if you could consult more widely before
> removing isolcpus as it will affect our users
> scattered through every country in the world.
>
>
> Rod Webster
> 1300 896 832
> +61 435 765 611
> VMN®
> www.vmn.com.au
>
> Rod Webster
> 1300 896 832
> +61 435 765 611
> VMN®
> www.vmn.com.au
>
> Sole Queensland Distributor
>
>
> On Thu, 28 Sept 2023 at 18:39, Sebastian Andrzej Siewior
> <bigeasy@xxxxxxxxxxxxx> wrote:
> >
> > On 2023-09-26 12:45:14 [-0400], Joseph Salisbury wrote:
> > > Hi All,
> > Hi,
> >
> > > I have a question regarding the isolcpus parameter. I've been seeing this
> > > parameter commonly used. However, in the kernel.org documentation[0],
> > > isolcpus is listed as depreciated.
> > >
> > > Is it the case that isolcpus should not be used at all? I've seen it used
> > > in conjunction with taskset. However, should we now be telling rt users to
> > > use only cpusets in cgroups? I see that CPUAffinity can be set in
> > > /etc/systemd/system.conf. Is that the preferred method, so the process
> > > scheduler will automatically migrate processes between the cpusets in the
> > > cgroup cpuset or the list set by CPUAffinity?
> >
> > Frederic might know if there is an actual timeline to remove it. The
> > suggestions since then is to use cpusets which should be more flexible.
> > There was also some work (which went into v6.1 I think) to be able to
> > reconfigure the partitions at run-time while isolcpus= is a boot time
> > option.
> > From what I remember, you have a default/system cpuset which all tasks
> > use by default and then you can add another cpuset for the "isolated"
> > CPUs. Based on the partition it can be either the default one or
> > isolated [0]. The latter would exclude the CPUs from load balancing
> > which is what isolcpus= does.
> >
> > [0] f28e22441f353 ("cgroup/cpuset: Add a new isolated cpus.partition type")
> >
> > > Thanks,
> > >
> > > Joe
> >
> > Sebastian
> >
>
--
Gautham Ponnu | http://gauthamponnu.com
