On Wed, Jul 29, 2020 at 3:54 PM Dumitrescu, Cristian <cristian.dumitre...@intel.com> wrote: > > -----Original Message----- > > From: David Marchand <david.march...@redhat.com> > > Sent: Wednesday, July 29, 2020 2:28 PM > > To: Dumitrescu, Cristian <cristian.dumitre...@intel.com> > > Cc: Xu, Ting <ting...@intel.com>; dev <dev@dpdk.org>; dpdk stable > > <sta...@dpdk.org>; Kevin Traynor <ktray...@redhat.com>; Luca Boccassi > > <bl...@debian.org> > > Subject: Re: [dpdk-stable] [dpdk-dev] [PATCH v4] lib/table: fix cache > > alignment issue > > > > On Wed, Jul 29, 2020 at 3:14 PM Dumitrescu, Cristian > > <cristian.dumitre...@intel.com> wrote: > > > > Please correct me if I am wrong, but it simply means this part of the > > > > table library never worked for 32-bit. > > > > It seems more adding 32-bit support rather than a fix and then I > > > > wonder if it has its place in rc3. > > > > > > > > > > Functionally. the code works, but performance is affected. > > > > > > The only thing that prevents the code from working is the check in the > > table create function that checks the size of the above structure is 64 > > bytes, > > which caught this issue. > > > > Yes, and that's my point. > > It was not working. > > It was not tested. > > > > > > Not sure when this code was last tested on 32-bit systems, I'll let the > validation folks comment on this, but I cannot rule out a change in compiler > behavior either. > > This is a low complexity and low impact change, hence low risk IMO.
Risk is to be evaluated when there is a need. I got pinged on this, like it was the end of the times. Then I find something that is not worth looking at, hence I am a bit irritated. And please, for the 2nd time, can you look at my comment below? > > > > > diff --git a/lib/librte_table/rte_table_hash_key16.c > > > > b/lib/librte_table/rte_table_hash_key16.c > > > > > index 2cca1c924..c4384b114 100644 > > > > > --- a/lib/librte_table/rte_table_hash_key16.c > > > > > +++ b/lib/librte_table/rte_table_hash_key16.c > > > > > @@ -33,6 +33,7 @@ > > > > > > > > > > #endif > > > > > > > > > > +#ifdef RTE_ARCH_64 > > > > > struct rte_bucket_4_16 { > > > > > /* Cache line 0 */ > > > > > uint64_t signature[4 + 1]; > > > > > @@ -46,6 +47,22 @@ struct rte_bucket_4_16 { > > > > > /* Cache line 2 */ > > > > > uint8_t data[0]; > > > > > }; > > > > > +#else > > > > > +struct rte_bucket_4_16 { > > > > > + /* Cache line 0 */ > > > > > + uint64_t signature[4 + 1]; > > > > > + uint64_t lru_list; > > > > > + struct rte_bucket_4_16 *next; > > > > > + uint32_t pad; > > > > > + uint64_t next_valid; > > > > > + > > > > > + /* Cache line 1 */ > > > > > + uint64_t key[4][2]; > > > > > + > > > > > + /* Cache line 2 */ > > > > > + uint8_t data[0]; > > > > > +}; > > > > > +#endif > > > > > > > > The change could simply be: > > > > > > > > @@ -38,6 +38,9 @@ struct rte_bucket_4_16 { > > > > uint64_t signature[4 + 1]; > > > > uint64_t lru_list; > > > > struct rte_bucket_4_16 *next; > > > > +#ifndef RTE_ARCH_64 > > > > + uint32_t pad; > > > > +#endif > > > > uint64_t next_valid; > > > > > > > > /* Cache line 1 */ > > > > > > > > It avoids duplicating the whole structure definition (we could miss > > > > updating one side of the #ifdef later). > > > > Idem for the other "8" and "32" structures. > > > > > > What about this comment? What about this comment? -- David Marchand