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

[John Levon <john.levon@nutanix.com>]

On Wed, Jul 07, 2021 at 11:06:05PM +0300, Dmitry Kozlyuk 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.
> > 
> > Signed-off-by: John Levon <john.levon@nutanix.com>
> > ---
> >  lib/eal/linux/eal_hugepage_info.c | 25 +++++++++++++++++++------
> >  1 file changed, 19 insertions(+), 6 deletions(-)
> > 
> > diff --git a/lib/eal/linux/eal_hugepage_info.c b/lib/eal/linux/eal_hugepage_info.c
> > index d97792cad..d7e9918f8 100644
> > --- a/lib/eal/linux/eal_hugepage_info.c
> > +++ b/lib/eal/linux/eal_hugepage_info.c
> > @@ -226,16 +226,29 @@ get_hugepage_dir(uint64_t hugepage_sz, char *hugedir, int len)
> >  		default_size = get_default_hp_size();
> >  
> >  	while (fgets(buf, sizeof(buf), fd)){
> > +		const char *dir;
> > +
> >  		if (rte_strsplit(buf, sizeof(buf), splitstr, _FIELDNAME_MAX,
> >  				split_tok) != _FIELDNAME_MAX) {
> >  			RTE_LOG(ERR, EAL, "Error parsing %s\n", proc_mounts);
> >  			break; /* return NULL */
> >  		}
> >  
> > -		/* we have a specified --huge-dir option, only examine that dir */
> > -		if (internal_conf->hugepage_dir != NULL &&
> > -				strcmp(splitstr[MOUNTPT], internal_conf->hugepage_dir) != 0)
> > -			continue;
> > +		dir = splitstr[MOUNTPT];
> > +
> > +		/*
> > +		 * If a --huge-dir option has been specified, only examine
> > +		 * mounts that contain that directory, and make sure to return
> > +		 * the directory, not the mount.
> > +		 */
> > +		if (internal_conf->hugepage_dir != NULL) {
> > +			if (strncmp(internal_conf->hugepage_dir,
> > +				splitstr[MOUNTPT],
> > +				strlen(splitstr[MOUNTPT])) != 0)
> > +				continue;
> > +
> > +			dir = internal_conf->hugepage_dir;
> > +		}
> 
> Suppose there are /mnt/huge and /mnt/huge-2M mounted with -o pagesize=2M.
> If --huge-dir=/mnt/huge-2M is specified, this code will select /mnt/huge.

Yeah, good spot. I'll change it to prefer closer matches or something.

> The code would be shorter with `splitstr[MOUNTPT]` -> `dir`.

Sure.

regards
john