RE: [PATCH v6] eal: allow worker lcore stacks to be allocated from hugepage memory

[Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>]

<snip>
> 
> 21/06/2022 16:52, Don Wallwork:
> > On 6/21/2022 10:42 AM, Thomas Monjalon wrote:
> > > 21/06/2022 14:31, Don Wallwork:
> > >> On 6/21/2022 6:37 AM, Thomas Monjalon wrote:
> > >>> 20/06/2022 10:35, David Marchand:
> > >>>> On Tue, May 24, 2022 at 9:52 PM Don Wallwork
> <donw@xsightlabs.com> wrote:
> > >>>>> Add support for using hugepages for worker lcore stack memory.
> > >>>>> The intent is to improve performance by reducing stack memory
> > >>>>> related TLB misses and also by using memory local to the NUMA node
> of each lcore.
> > >>>>> EAL option '--huge-worker-stack [stack-size-in-kbytes]' is added
> > >>>>> to allow the feature to be enabled at runtime.  If the size is
> > >>>>> not specified, the system pthread stack size will be used.
> > >>>> - About the name of the option... I don't have a better name.
> > >>>>
> > >>>> Just want to highlight, that what this patch does is use the DPDK
> > >>>> memory allocator for the stack memory.
> > >>>> It happens that DPDK memory allocator is primarily used with
> > >>>> hugepages, but this is not systematic for example with the "no-huge"
> > >>>> mode of the DPDK memory allocator.
> > >>>>
> > >>>> IOW, in this patch current form, you can still run as:
> > >>>>
> > >>>> # dpdk-testpmd -c 3 --no-huge --huge-worker-stack=16 -m 40 -- etc...
> > >>>>
> > >>>> Opinions?
> > >>> The name of the option should not include "huge".
> > >>> What about "--worker-stack" ?
> > >>> If disabled (equal zero), the workers should use the default stack memory.
> > >>>
> > >>>
> > >> Wouldn't that have the potential to create confusion?  The point of
> > >> this change is to allocate worker stacks from hugepages.  Removing
> > >> huge from the option name could give the impression that the
> > >> command is simply to control worker stack size.
> > > It means if we control the worker stack size with a DPDK option,
> > > DPDK memory will be used.
> > > But we cannot force hugepage with this option.
> > > Hugepage is not always available and it can be disabled in DPDK.
> >
> > The command could be rejected if hugepages are not available.
> > That's not in the patch currently, but can be added.
> 
> David, Anatoly, Dmitry, what do you think?
> 
It should be a warning, but the application can continue to run

> 
>