Hi Haiyue, On Fri, Oct 18, 2019 at 02:47:50AM +0000, Wang, Haiyue wrote: > Hi Olivier > > > -----Original Message----- > > From: Olivier Matz [mailto:olivier.m...@6wind.com] > > Sent: Thursday, October 17, 2019 22:42 > > To: dev@dpdk.org > > Cc: Andrew Rybchenko <arybche...@solarflare.com>; Richardson, Bruce > > <bruce.richard...@intel.com>; Wang, > > Haiyue <haiyue.w...@intel.com>; Jerin Jacob Kollanukkaran > > <jer...@marvell.com>; Wiles, Keith > > <keith.wi...@intel.com>; Ananyev, Konstantin > > <konstantin.anan...@intel.com>; Morten Brørup > > <m...@smartsharesystems.com>; Stephen Hemminger > > <step...@networkplumber.org>; Thomas Monjalon > > <tho...@monjalon.net> > > Subject: [PATCH v2] mbuf: support dynamic fields and flags > > > > Many features require to store data inside the mbuf. As the room in mbuf > > structure is limited, it is not possible to have a field for each > > feature. Also, changing fields in the mbuf structure can break the API > > or ABI. > > > > This commit addresses these issues, by enabling the dynamic registration > > of fields or flags: > > > > - a dynamic field is a named area in the rte_mbuf structure, with a > > given size (>= 1 byte) and alignment constraint. > > - a dynamic flag is a named bit in the rte_mbuf structure. > > > > The typical use case is a PMD that registers space for an offload > > feature, when the application requests to enable this feature. As > > the space in mbuf is limited, the space should only be reserved if it > > is going to be used (i.e when the application explicitly asks for it). > > > > The registration can be done at any moment, but it is not possible > > to unregister fields or flags for now. > > > > Signed-off-by: Olivier Matz <olivier.m...@6wind.com> > > Acked-by: Thomas Monjalon <tho...@monjalon.net> > > --- > > > > v2 > > > > * Rebase on top of master: solve conflict with Stephen's patchset > > (packet copy) > > * Add new apis to register a dynamic field/flag at a specific place > > * Add a dump function (sugg by David) > > * Enhance field registration function to select the best offset, keeping > > large aligned zones as much as possible (sugg by Konstantin) > > * Use a size_t and unsigned int instead of int when relevant > > (sugg by Konstantin) > > * Use "uint64_t dynfield1[2]" in mbuf instead of 2 uint64_t fields > > (sugg by Konstantin) > > * Remove unused argument in private function (sugg by Konstantin) > > * Fix and simplify locking (sugg by Konstantin) > > * Fix minor typo > > > > rfc -> v1 > > > > * Rebase on top of master > > * Change registration API to use a structure instead of > > variables, getting rid of #defines (Stephen's comment) > > * Update flag registration to use a similar API as fields. > > * Change max name length from 32 to 64 (sugg. by Thomas) > > * Enhance API documentation (Haiyue's and Andrew's comments) > > * Add a debug log at registration > > * Add some words in release note > > * Did some performance tests (sugg. by Andrew): > > On my platform, reading a dynamic field takes ~3 cycles more > > than a static field, and ~2 cycles more for writing. > > > > app/test/test_mbuf.c | 145 ++++++- > > doc/guides/rel_notes/release_19_11.rst | 7 + > > lib/librte_mbuf/Makefile | 2 + > > lib/librte_mbuf/meson.build | 6 +- > > lib/librte_mbuf/rte_mbuf.h | 23 +- > > lib/librte_mbuf/rte_mbuf_dyn.c | 548 +++++++++++++++++++++++++ > > lib/librte_mbuf/rte_mbuf_dyn.h | 226 ++++++++++ > > lib/librte_mbuf/rte_mbuf_version.map | 7 + > > 8 files changed, 959 insertions(+), 5 deletions(-) > > create mode 100644 lib/librte_mbuf/rte_mbuf_dyn.c > > create mode 100644 lib/librte_mbuf/rte_mbuf_dyn.h > > > > diff --git a/app/test/test_mbuf.c b/app/test/test_mbuf.c > > index b9c2b2500..01cafad59 100644 > > --- a/app/test/test_mbuf.c > > +++ b/app/test/test_mbuf.c > > @@ -28,6 +28,7 @@ > > #include <rte_random.h> > > [snip] > > > +/** > > + * Helper macro to access to a dynamic field. > > + */ > > +#define RTE_MBUF_DYNFIELD(m, offset, type) ((type)((uintptr_t)(m) + > > (offset))) > > + > > The suggested macro is missed ? ;-) > /** > * Helper macro to access to a dynamic flag. > */ > #define RTE_MBUF_DYNFLAG(offset) (1ULL << (offset))
Yes, sorry. Thinking a bit more about it, I wonder if the macros below aren't more consistent with the dynamic field (because they take the mbuf as parameter)? #define RTE_MBUF_SET_DYNFLAG(m, bitnum, val) ... #define RTE_MBUF_GET_DYNFLAG(m, bitnum) ... They could even be static inline functions. On the other hand, these helpers would be generic to ol_flags, not only for dynamic flags. Today, we use (1ULL << bit) for ol_flags, which makes me wonder... is the macro really needed after all? :) > BTW, should we have a place to put the registered dynamic fields and flags > names together (a name overview -- detail Link to --> PMD's help page) ? The centralized place will be in rte_mbuf_dyn.h for fields/flags that can are shared between several dpdk areas. Some libraries/pmd could have private dynamic fields/flags. In any case, I think the same namespace than functions should be used. Probably something like this: - "rte_mbuf_dynfield_<name>" in mbuf lib - "rte_<libname>_dynfield_<name>" in other libs - "rte_net_<pmd>_dynfield_<name>" in pmds - "<name>" in apps > Since rte_mbuf_dynfield:name & rte_mbuf_dynflag:name work as a API style, > users can check how many 'names' registered, developers can check whether > the names they want to use are registered or not ? They don't need to have > to check the rte_errno ... Just a suggestion for user experience. I did not get you point. Does my response above answers to your question? Regards, Olivier
