nft_set_pipapo: Introduce AVX2-based lookup implementation

If the AVX2 set is available, we can exploit the repetitive
characteristic of this algorithm to provide a fast, vectorised
version by using 256-bit wide AVX2 operations for bucket loads and
bitwise intersections.

In most cases, this implementation consistently outperforms rbtree
set instances despite the fact they are configured to use a given,
single, ranged data type out of the ones used for performance
measurements by the nft_concat_range.sh kselftest.

That script, injecting packets directly on the ingoing device path
with pktgen, reports, averaged over five runs on a single AMD Epyc
7402 thread (3.35GHz, 768 KiB L1D$, 12 MiB L2$), the figures below.
CONFIG_RETPOLINE was not set here.

Note that this is not a fair comparison over hash and rbtree set
types: non-ranged entries (used to have a reference for hash types)
would be matched faster than this, and matching on a single field
only (which is the case for rbtree) is also significantly faster.

However, it's not possible at the moment to choose this set type
for non-ranged entries, and the current implementation also needs
a few minor adjustments in order to match on less than two fields.

 ---------------.-----------------------------------.------------.
 AMD Epyc 7402  |          baselines, Mpps          | this patch |
  1 thread      |___________________________________|____________|
  3.35GHz       |        |        |        |        |            |
  768KiB L1D$   | netdev |  hash  | rbtree |        |            |
 ---------------|  hook  |   no   | single |        |   pipapo   |
 type   entries |  drop  | ranges | field  | pipapo |    AVX2    |
 ---------------|--------|--------|--------|--------|------------|
 net,port       |        |        |        |        |            |
          1000  |   19.0 |   10.4 |    3.8 |    4.0 | 7.5   +87% |
 ---------------|--------|--------|--------|--------|------------|
 port,net       |        |        |        |        |            |
           100  |   18.8 |   10.3 |    5.8 |    6.3 | 8.1   +29% |
 ---------------|--------|--------|--------|--------|------------|
 net6,port      |        |        |        |        |            |
          1000  |   16.4 |    7.6 |    1.8 |    2.1 | 4.8  +128% |
 ---------------|--------|--------|--------|--------|------------|
 port,proto     |        |        |        |        |            |
         30000  |   19.6 |   11.6 |    3.9 |    0.5 | 2.6  +420% |
 ---------------|--------|--------|--------|--------|------------|
 net6,port,mac  |        |        |        |        |            |
            10  |   16.5 |    5.4 |    4.3 |    3.4 | 4.7   +38% |
 ---------------|--------|--------|--------|--------|------------|
 net6,port,mac, |        |        |        |        |            |
 proto    1000  |   16.5 |    5.7 |    1.9 |    1.4 | 3.6   +26% |
 ---------------|--------|--------|--------|--------|------------|
 net,mac        |        |        |        |        |            |
          1000  |   19.0 |    8.4 |    3.9 |    2.5 | 6.4  +156% |
 ---------------'--------'--------'--------'--------'------------'

A similar strategy could be easily reused to implement specialised
versions for other SIMD sets, and I plan to post at least a NEON
version at a later time.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 24 insertions, 0 deletions

diff --git a/net/netfilter/nft_set_pipapo.c b/net/netfilter/nft_set_pipapo.c
index 141e0ab26d3c..1e8dd5dccdf7 100644
--- a/net/netfilter/nft_set_pipapo.c
+++ b/net/netfilter/nft_set_pipapo.c
@@ -339,6 +339,7 @@
 #include <linux/bitmap.h>
 #include <linux/bitops.h>
 
+#include "nft_set_pipapo_avx2.h"
 #include "nft_set_pipapo.h"
 
 /* Current working bitmap index, toggled between field matches */
@@ -2174,3 +2175,26 @@ const struct nft_set_type nft_set_pipapo_type = {
 		.elemsize	= offsetof(struct nft_pipapo_elem, ext),
 	},
 };
+
+#if defined(CONFIG_X86_64) && defined(CONFIG_AS_AVX2)
+const struct nft_set_type nft_set_pipapo_avx2_type = {
+	.features	= NFT_SET_INTERVAL | NFT_SET_MAP | NFT_SET_OBJECT |
+			  NFT_SET_TIMEOUT,
+	.ops		= {
+		.lookup		= nft_pipapo_avx2_lookup,
+		.insert		= nft_pipapo_insert,
+		.activate	= nft_pipapo_activate,
+		.deactivate	= nft_pipapo_deactivate,
+		.flush		= nft_pipapo_flush,
+		.remove		= nft_pipapo_remove,
+		.walk		= nft_pipapo_walk,
+		.get		= nft_pipapo_get,
+		.privsize	= nft_pipapo_privsize,
+		.estimate	= nft_pipapo_avx2_estimate,
+		.init		= nft_pipapo_init,
+		.destroy	= nft_pipapo_destroy,
+		.gc_init	= nft_pipapo_gc_init,
+		.elemsize	= offsetof(struct nft_pipapo_elem, ext),
+	},
+};
+#endif