Re: [dpdk-dev] [EXT] Re: [PATCH v6 0/4] add IOVA = VA support in KNI

[Jerin Jacob Kollanukkaran <jerinj@marvell.com>]

> -----Original Message-----
> From: Burakov, Anatoly <anatoly.burakov@intel.com>
> Sent: Friday, July 12, 2019 5:40 PM
> To: Jerin Jacob Kollanukkaran <jerinj@marvell.com>; Ferruh Yigit
> <ferruh.yigit@intel.com>; Vamsi Krishna Attunuru
> <vattunuru@marvell.com>; dev@dpdk.org
> Cc: olivier.matz@6wind.com; arybchenko@solarflare.com
> Subject: [EXT] Re: [dpdk-dev] [PATCH v6 0/4] add IOVA = VA support in KNI
> 
> External Email
> 
> ----------------------------------------------------------------------
> On 12-Jul-19 12:37 PM, Jerin Jacob Kollanukkaran wrote:
> >> -----Original Message-----
> >> From: Burakov, Anatoly <anatoly.burakov@intel.com>
> >> Sent: Friday, July 12, 2019 4:19 PM
> >> To: Jerin Jacob Kollanukkaran <jerinj@marvell.com>; Ferruh Yigit
> >> <ferruh.yigit@intel.com>; Vamsi Krishna Attunuru
> >> <vattunuru@marvell.com>; dev@dpdk.org
> >> Cc: olivier.matz@6wind.com; arybchenko@solarflare.com
> >> Subject: [EXT] Re: [dpdk-dev] [PATCH v6 0/4] add IOVA = VA support in
> >> KNI On 12-Jul-19 11:26 AM, Jerin Jacob Kollanukkaran wrote:
> >>>>>> What do you think?
> >>>>>
> >>>>> IMO, If possible we can avoid extra indirection of new config. In
> >>>>> worst case We can add it. How about following to not have new
> >>>>> config
> >>>>>
> >>>>> 1) Make MEMPOOL_F_NO_PAGE_BOUND  as default
> >>>>> http://patches.dpdk.org/patch/55277/
> >>>>> There is absolutely zero overhead of this flag considering the
> >>>>> huge page size are minimum 2MB. Typically 512MB or 1GB.
> >>>>> Any one has any objection?
> >>>>
> >>>> Pretty much zero overhead in hugepage case, not so in non-hugepage
> >> case.
> >>>> It's rare, but since we support it, we have to account for it.
> >>>
> >>> That is a fair concern.
> >>> How about enable the flag in mempool ONLY when
> >> rte_eal_has_hugepages()
> >>> In the common layer?
> >>
> >> Perhaps it's better to check page size of the underlying memory,
> >> because 4K pages are not necessarily no-huge mode - they could also
> >> be external memory. That's going to be a bit hard because there may
> >> not be a way to know which memory we're allocating from in advance,
> >> aside from simple checks like `(rte_eal_has_hugepages() ||
> >> rte_malloc_heap_socket_is_external(socket_id))` - but maybe those
> >> would be sufficient.
> >
> > Yes.
> >
> >
> >>
> >>>
> >>>> (also, i don't really like the name NO_PAGE_BOUND since in memzone
> >>>> API there's a "bounded memzone" allocation API, and this flag's
> >>>> name reads like objects would not be bounded by page size, not that
> >>>> they won't cross page
> >>>> boundary)
> >>>
> >>> No strong opinion for the name. What name you suggest?
> >>
> >> How about something like MEMPOOL_F_NO_PAGE_SPLIT?
> >
> > Looks good to me.
> >
> > In summary, Change wrt existing patch"
> > - Change NO_PAGE_BOUND to MEMPOOL_F_NO_PAGE_SPLIT
> > - Set this flag in  rte_pktmbuf_pool_create () when
> rte_eal_has_hugepages() ||
> >   rte_malloc_heap_socket_is_external(socket_id))
> 
> If we are to have a special KNI allocation API, would we even need that?

Not need this change in rte_pktmbuf_pool_create () if we introduce
a new rte_kni_pktmbuf_pool_create () API.

> 
> >
> > Olivier, Any objection?
> > Ref: http://patches.dpdk.org/patch/55277/
> >
> 
> 
> 
> --
> Thanks,
> Anatoly