Comment # 7 on bug 1206937 from Mel Gorman

(In reply to John Doe from comment #5)
> (In reply to Michal Hocko from comment #2)
> > (In reply to John Doe from comment #0)
> > > Enabling MGLRU could give some performance benefits. Right now it is
> > > compiled into the kernel but not enabled by default
> > 
> > Do you have any specific usecase in mind or is this more of a "I want to
> > play with this new reclaim implementation"?
> 
> No specific use case but others might find this useful due to the
> performance benefits. Arch enabled it already and I presume Fedora will have
> it enabled when 6.1 reaches Fedora 37

As far as I'm aware, the main benefits have been demonstrated on relatively
small machines with desktop-class workloads -- primarily workloads interesting
to a chromebook where interactive tasks perform better when the total working
set for foreground and background tasks exceeds total memory. That's a less
common scenario then what is seen on server class workloads. For example, one
of our biggest customers by revenue has applications that carefully size their
workload to avoid swapping and reclaim decisions as much as possible and MGLRU
would have limited to no benefit. Hence the caution about enabling it by
default because it could take years to rattle out the issues. However, the
option to enable it and experiment it is available so if a few requests were
made based on "Workload X benefits from MGLRU and we should not have to tune it
every time" then there would be greater confidence in enabling it by default.