> -----Original Message----- > From: Stephen Hemminger [mailto:step...@networkplumber.org] > Sent: Wednesday, October 23, 2019 23:00 > To: Olivier Matz <olivier.m...@6wind.com> > Cc: Wang, Haiyue <haiyue.w...@intel.com>; Ananyev, Konstantin > <konstantin.anan...@intel.com>; > dev@dpdk.org; Andrew Rybchenko <arybche...@solarflare.com>; Richardson, Bruce > <bruce.richard...@intel.com>; Jerin Jacob Kollanukkaran <jer...@marvell.com>; > Wiles, Keith > <keith.wi...@intel.com>; Morten Brørup <m...@smartsharesystems.com>; Thomas > Monjalon > <tho...@monjalon.net> > Subject: Re: [PATCH v2] mbuf: support dynamic fields and flags > > On Wed, 23 Oct 2019 12:21:43 +0200 > Olivier Matz <olivier.m...@6wind.com> wrote: > > > On Wed, Oct 23, 2019 at 03:16:13AM +0000, Wang, Haiyue wrote: > > > > -----Original Message----- > > > > From: Ananyev, Konstantin > > > > Sent: Wednesday, October 23, 2019 06:52 > > > > To: Olivier Matz <olivier.m...@6wind.com>; 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>; Morten Brørup <m...@smartsharesystems.com>; > > > > Stephen Hemminger > > > > <step...@networkplumber.org>; Thomas Monjalon <tho...@monjalon.net> > > > > Subject: RE: [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> > > > > > #include <rte_cycles.h> > > > > > #include <rte_malloc.h> > > > > > +#include <rte_mbuf_dyn.h> > > > > > > > > > > > [snip] > > > > > +int > > > > > +rte_mbuf_dynflag_register_bitnum(const struct rte_mbuf_dynflag > > > > > *params, > > > > > + unsigned int req) > > > > > +{ > > > > > + int ret; > > > > > + > > > > > + if (req != UINT_MAX && req >= 64) { > > > > > > > > Might be better to replace 64 with something like > > > > sizeof(mbuf->ol_flags) * CHAR_BIT or so. > > > > > > Might introduce a new macro like kernel: > > > > > > /** > > > * FIELD_SIZEOF - get the size of a struct's field > > > * @t: the target struct > > > * @f: the target struct's field > > > * Return: the size of @f in the struct definition without having a > > > * declared instance of @t. > > > */ > > > #define FIELD_SIZEOF(t, f) (sizeof(((t*)0)->f)) > > > > > > Then: FIELD_SIZEOF(rte_mbuf, ol_flags) * CHAR_BIT > > > > Good idea, thanks > > > > Kernel is replacing FIELD_SIZEOF with sizeof_member
Yes, but looks like in 5.5 ? 5.4 hasn't merged. ;-) https://www.phoronix.com/scan.php?page=news_item&px=Linux-5.4-Size-Of-Member https://patchwork.kernel.org/patch/11184583/ +/** + * sizeof_member(TYPE, MEMBER) - get the size of a struct's member + * + * @TYPE: the target struct + * @MEMBER: the target struct's member + * + * Return: the size of @MEMBER in the struct definition without having a + * declared instance of @TYPE. + */ +#define sizeof_member(TYPE, MEMBER) (sizeof(((TYPE *)0)->MEMBER))
