diff options
| author | Eric Dumazet <edumazet@google.com> | 2025-03-21 17:13:09 +0000 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2025-03-25 08:24:13 -0700 |
| commit | f3483c8e1da62993fe0f57af23b925de7661adaa (patch) | |
| tree | 3d864c054b3ebe3c8eecda735e3b235851214994 /net/core/net-sysfs.c | |
| parent | 1952e19c02ae8ea0c663d30b19be14344b543068 (diff) | |
net: rfs: hash function change
RFS is using two kinds of hash tables.
First one is controlled by /proc/sys/net/core/rps_sock_flow_entries = 2^N
and using the N low order bits of the l4 hash is good enough.
Then each RX queue has its own hash table, controlled by
/sys/class/net/eth1/queues/rx-$q/rps_flow_cnt = 2^X
Current hash function, using the X low order bits is suboptimal,
because RSS is usually using Func(hash) = (hash % power_of_two);
For example, with 32 RX queues, 6 low order bits have no entropy
for a given queue.
Switch this hash function to hash_32(hash, log) to increase
chances to use all possible slots and reduce collisions.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Tom Herbert <tom@herbertland.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250321171309.634100-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/core/net-sysfs.c')
| -rw-r--r-- | net/core/net-sysfs.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c index abaa1c919b98..b6fbe629ccee 100644 --- a/net/core/net-sysfs.c +++ b/net/core/net-sysfs.c @@ -1056,7 +1056,7 @@ static ssize_t show_rps_dev_flow_table_cnt(struct netdev_rx_queue *queue, rcu_read_lock(); flow_table = rcu_dereference(queue->rps_flow_table); if (flow_table) - val = (unsigned long)flow_table->mask + 1; + val = 1UL << flow_table->log; rcu_read_unlock(); return sysfs_emit(buf, "%lu\n", val); @@ -1109,7 +1109,7 @@ static ssize_t store_rps_dev_flow_table_cnt(struct netdev_rx_queue *queue, if (!table) return -ENOMEM; - table->mask = mask; + table->log = ilog2(mask) + 1; for (count = 0; count <= mask; count++) table->flows[count].cpu = RPS_NO_CPU; } else { |