From: David Marchand <david.marchand@redhat.com> To: Ting Xu <ting.xu@intel.com>, Cristian Dumitrescu <cristian.dumitrescu@intel.com> Cc: dev <dev@dpdk.org>, dpdk stable <stable@dpdk.org> Subject: Re: [dpdk-dev] [PATCH v4] lib/table: fix cache alignment issue Date: Wed, 29 Jul 2020 14:01:25 +0200 Message-ID: <CAJFAV8zZRQEjVGp07NzuraHuA9YWWK_6VZZ5hN69w2GQuFeTeQ@mail.gmail.com> (raw) In-Reply-To: <20200722021628.17194-1-ting.xu@intel.com> On Wed, Jul 22, 2020 at 4:13 AM Ting Xu <ting.xu@intel.com> wrote: > > When create softnic hash table with 16 keys, it failed on 32-bit > environment, because the pointer field in structure rte_bucket_4_16 > is only 32 bits. Add a padding field in 32-bit environment to keep > the structure to a multiple of 64 bytes. Apply this to 8-byte and > 32-byte key hash function as well. 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. Now, looking at the details: For 64-bit on my x86, we have: struct rte_bucket_4_8 { uint64_t signature; /* 0 8 */ uint64_t lru_list; /* 8 8 */ struct rte_bucket_4_8 * next; /* 16 8 */ uint64_t next_valid; /* 24 8 */ uint64_t key[4]; /* 32 32 */ /* --- cacheline 1 boundary (64 bytes) --- */ uint8_t data[]; /* 64 0 */ /* size: 64, cachelines: 1, members: 6 */ }; For 32-bit, we have: struct rte_bucket_4_8 { uint64_t signature; /* 0 8 */ uint64_t lru_list; /* 8 8 */ struct rte_bucket_4_8 * next; /* 16 4 */ uint64_t next_valid; /* 20 8 */ uint64_t key[4]; /* 28 32 */ uint8_t data[]; /* 60 0 */ /* size: 60, cachelines: 1, members: 6 */ /* last cacheline: 60 bytes */ } __attribute__((__packed__)); ^^ it is interesting that a packed attribute ends up here. I saw no such attribute in the library code. Compiler black magic at work I guess... > > Fixes: 8aa327214c ("table: hash") > Cc: stable@dpdk.org > > Signed-off-by: Ting Xu <ting.xu@intel.com> > > --- > v3->v4: Change design based on comment > v2->v3: Rebase > v1->v2: Correct patch time > --- > lib/librte_table/rte_table_hash_key16.c | 17 +++++++++++++++++ > lib/librte_table/rte_table_hash_key32.c | 17 +++++++++++++++++ > lib/librte_table/rte_table_hash_key8.c | 16 ++++++++++++++++ > 3 files changed, 50 insertions(+) > > 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. -- David Marchand
next prev parent reply other threads:[~2020-07-29 12:01 UTC|newest] Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-06-16 16:27 [dpdk-dev] [PATCH v1] " Ting Xu 2020-06-17 5:43 ` [dpdk-dev] [PATCH v2] " Ting Xu 2020-07-02 8:06 ` Zhou, JunX W 2020-07-09 1:48 ` [dpdk-dev] [PATCH v3] " Ting Xu 2020-07-20 14:37 ` Dumitrescu, Cristian 2020-07-21 5:15 ` Xu, Ting 2020-07-21 21:16 ` Dumitrescu, Cristian 2020-07-22 2:16 ` Xu, Ting 2020-07-22 2:16 ` [dpdk-dev] [PATCH v4] " Ting Xu 2020-07-22 8:26 ` Dumitrescu, Cristian 2020-07-22 8:30 ` Xu, Ting 2020-07-22 8:49 ` Dumitrescu, Cristian 2020-07-22 8:48 ` Dumitrescu, Cristian 2020-07-29 12:01 ` David Marchand [this message] 2020-07-29 13:13 ` Dumitrescu, Cristian 2020-07-29 13:28 ` [dpdk-dev] [dpdk-stable] " David Marchand 2020-07-29 13:54 ` Dumitrescu, Cristian 2020-07-29 13:59 ` David Marchand 2020-07-29 14:53 ` Dumitrescu, Cristian 2020-07-30 6:57 ` Xu, Ting 2020-07-30 10:35 ` Kevin Traynor 2020-09-09 6:18 ` Xu, Ting 2020-09-15 8:03 ` David Marchand 2020-10-14 8:26 ` Xu, Ting 2020-10-14 13:53 ` [dpdk-dev] " David Marchand
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