I’m thinking different usage for these. The context pointer (odp_packet_userctx_ptr()) would point to some data structure in the memory, where as odp_packet_userarea() would be used as a per packet scratchpad memory. When implementation knows that the user stores a pointer, it can also prefetch the data behind the pointer. If the pointer is saved as part of the userarea, implementation cannot know where it is. Other advantage comes from get/set accessors vs random memory access – bits can be packed freely vs. must be contiguous with certain (8 byte) alignment. Enabling prefething is likely more important for performance, than bit packing. For shorter/cleaner API, we could drop _userctx_u64().
-Petri From: ext Bill Fischofer [mailto:[email protected]] Sent: Wednesday, April 22, 2015 2:46 PM To: Savolainen, Petri (Nokia - FI/Espoo) Cc: ext Zoltan Kiss; [email protected] Subject: Re: [lng-odp] [API-NEXT PATCHv4 0/6] Add packet user metadata support I'm not sure why we wouldn't want to just deprecate the odp_packet_user_ptr/_u64() calls. They were stopgaps since we didn't have user metadata in v1.0. Now that we have that, what's the purpose of keeping the earlier calls? The latter is a more flexible and capable feature, and can be equally efficient for small user metadata areas (implementation choice). On Wed, Apr 22, 2015 at 6:37 AM, Savolainen, Petri (Nokia - FI/Espoo) <[email protected]<mailto:[email protected]>> wrote: Hi, After thinking this again, it's cleaner for the API (and the user) if these two user metadata fields are kept separate (as they currently are). The user_ptr/_u64 is always present and user_data only when param.pkt.udata_size is non-zero. Implementations have different ways to store both of these into the packet descriptor (maybe pointer to user_data is not needed, but it can be found with a fixed offset, etc). However the naming of these two could be cleaner (== highlight the dependencies): - odp_packet_user_ptr/_u64() could be renamed to odp_packet_userctx_ptr/_u64() - odp_packet_user_data/_data_size() could be renamed to odp_packet_userarea/userarea_size() - we should avoid confusion with similar terms in DPDK - mbuf.userdata == current odp_packet_user_ptr() - mbuf.udata64 == current odp_packet_user_u64() Opinions? I can send a patch for renames and documentation improvements. -Petri > -----Original Message----- > From: ext Zoltan Kiss > [mailto:[email protected]<mailto:[email protected]>] > Sent: Tuesday, April 21, 2015 4:08 PM > To: Bill Fischofer; > [email protected]<mailto:[email protected]>; Savolainen, Petri > (Nokia - > FI/Espoo) > Subject: Re: [lng-odp] [API-NEXT PATCHv4 0/6] Add packet user metadata > support > > It seems to me all questions were answered, is there anything which > prevents applying this into master branch? > Petri? > > On 10/04/15 16:52, Bill Fischofer wrote: > > v4 changes: > > - Removed RFC status, patch is now ready for API-NEXT > > - Added implementation of approved APIs > > - Added user metadata tests to packet validation test > > > > v3 changes: > > - Renamed odp_packet_user_metadata() to odp_packet_user_data() > > - Split addr/size return, adding odp_packet_user_data_size() > > - Moved udata_size to pkt structure within odp_pool_param_t > > > > v2 changes: > > - Moved udata_size to odp_pool_param_t > > - Renamed odp_packet_udata() to odp_packet_user_metadata() > > - Removed odp_buffer_udata(). User metadata is for packets only > > > > RFC for proposed minimal API set for user metadata support > > based on today's discussions. Note that all initialization > > and management of user metadata contents is the responsibility of > > the ODP application. ODP APIs that copy system metadata will also > > copy any associated user metadata as part of that operation, but > > ODP will otherwise ignore these bytes. > > > > Bill Fischofer (6): > > api: packet: add user metadata APIs > > api: pool: add user metadata APIs > > linux-generic: buffer: restructure user mdatadata fields > > linux-generic: pool: add user metadata support > > linux-generic: packet: add user metadata support > > validation: packet: add user metadata tests > > > > include/odp/api/packet.h | 20 ++++++++ > > include/odp/api/pool.h | 4 ++ > > .../linux-generic/include/odp_buffer_internal.h | 4 +- > > platform/linux-generic/include/odp_pool_internal.h | 2 +- > > platform/linux-generic/odp_packet.c | 34 ++++++++++++++ > > platform/linux-generic/odp_pool.c | 34 +++++--------- > > test/validation/odp_packet.c | 54 > ++++++++++++++++++++++ > > 7 files changed, 126 insertions(+), 26 deletions(-) > >
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