Re: [PATCH v2] eal/linux: enable the hugepage mem dump

[Dmitry Kozlyuk <dmitry.kozliuk@gmail.com>]

2022-04-05 15:46 (UTC-0700), Stephen Hemminger:
> On Fri,  1 Apr 2022 17:10:04 +0800
> Li Feng <fengli@smartx.com> wrote:
> 
> > These hugepages include important structures. we should dump these
> > hugepages into a coredump file for debugging when generating a coredump.
> > 
> > Signed-off-by: Li Feng <fengli@smartx.com>
> > ---
> >  lib/eal/linux/eal_memalloc.c | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/lib/eal/linux/eal_memalloc.c b/lib/eal/linux/eal_memalloc.c
> > index f8b1588cae..93c4f396cf 100644
> > --- a/lib/eal/linux/eal_memalloc.c
> > +++ b/lib/eal/linux/eal_memalloc.c
> > @@ -677,6 +677,8 @@ alloc_seg(struct rte_memseg *ms, void *addr, int socket_id,
> >  				__func__);
> >  #endif
> >  
> > +	eal_mem_set_dump(addr, alloc_sz, true);
> > +
> >  	huge_recover_sigbus();
> >  
> >  	ms->addr = addr;  
> 
> 
> Don't merge this patch as is please; it would cause a lot of pain
> in a cloud environment.
> 
> In our environment core dumps are collected (via systemd) and uploaded
> to a central server. With this kind of change the processing would get
> overloaded with multi-gigabyte core dump size. Probably couldn't even
> save a core dump on these kind of smart nics.
> 
> 
> This needs to be optional (from command line) and default to the current
> behavior (not dumping huge pages).

Maybe expose eal_mem_set_dump() as rte_mem_set_dump()?
This would allow to implement the feature easily using memory callbacks.
Better, one can enable hugepages to dump selectively:
for example, dump some interesting hash tables but skip rings and mempools.