Re: [dpdk-dev] [PATCH v3] eal: allow hugetlbfs sub-directories

[Thomas Monjalon <thomas@monjalon.net>]

22/07/2021 23:06, John Levon:
> On Thu, Jul 22, 2021 at 10:29:45PM +0200, David Marchand wrote:
> 
> > On Thu, Jul 8, 2021 at 1:00 PM John Levon <john.levon@nutanix.com> wrote:
> > >
> > > get_hugepage_dir() was implemented in such a way that a --huge-dir
> > > option had to exactly match the mountpoint, but there's no reason for
> > > this restriction. Fix the implementation to allow a sub-directory within
> > > a suitable hugetlbfs mountpoint to be specified, preferring the closest
> > > match.
> > >
> > > Signed-off-by: John Levon <john.levon@nutanix.com>
> > 
> > This change in EAL hugetlbfs discovery is too dangerous to be taken after -rc1.
> 
> Sure.
> 
> > Could you give some usecases/examples on why this change is needed?
> 
> Would you like me to expand the commit message?

Yes please add some examples of directories explaining the issue you hit.

> I had hoped it was clear enough,
> but I suppose not. Simply put, DPDK above is assuming its the only user of
> hugepages on the system - including clear_hugedir(). That is certainly not the
> case for our use cases.
> 
> > Updating the documentation
> 
> https://doc.dpdk.org/guides/linux_gsg/linux_eal_parameters.html
> 
> """
> --huge-dir <path to hugetlbfs directory>
> 
> Use specified hugetlbfs directory instead of autodetected ones.
> """
> 
> That is, it already says "directory", not "mount". You'd like something
> additional saying it can be below a mount point?

Yes

> > and the unit test also seem necessary.
> 
> You're talking about app/test/test_eal_flags.c or something else?

Yes

Thanks