target/linux/generic/hack-4.14/600-net-core-add-RPS-balancer.patch

   1 From 3e969c9695b45e1a052d43b367096ec99f2f0aac Mon Sep 17 00:00:00 2001
   2 From: John Crispin <john@phrozen.org>
   3 Date: Thu, 10 Aug 2017 15:58:29 +0200
   4 Subject: [PATCH] net: core: add RPS balancer
   5
   6 This patch adds a hash bucket based rps hash balancer.
   7
   8 Signed-off-by: John Crispin <john@phrozen.org>
   9 ---
  10  net/core/dev.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
  11  1 file changed, 56 insertions(+), 1 deletion(-)
  12
  13 --- a/net/core/dev.c
  14 +++ b/net/core/dev.c
  15 @@ -3626,6 +3626,58 @@ set_rps_cpu(struct net_device *dev, stru
  16         return rflow;
  17  }
  18
  19 +#define RPS_TBL_SIZE_SHIFT     10
  20 +#define RPS_TBL_SIZE           (1 << RPS_TBL_SIZE_SHIFT)
  21 +struct rps_table {
  22 +       int                     core;
  23 +       struct timer_list       expire;
  24 +};
  25 +static struct rps_table rps_table[RPS_TBL_SIZE];
  26 +static int rps_table_last_core;
  27 +
  28 +static void rps_table_expire(unsigned long data)
  29 +{
  30 +       struct rps_table *entry = (struct rps_table *) data;
  31 +
  32 +       entry->core = -1;
  33 +}
  34 +
  35 +static int rps_table_core(struct rps_map *map)
  36 +{
  37 +       int i;
  38 +
  39 +       for (i = 0; i < map->len; i++) {
  40 +               int cpu = map->cpus[(rps_table_last_core + i + 1) % map->len];
  41 +               if (cpu_online(cpu)) {
  42 +                       rps_table_last_core = cpu;
  43 +                       return cpu;
  44 +               }
  45 +       }
  46 +       return map->cpus[0];
  47 +}
  48 +
  49 +static int rps_table_lookup(struct rps_map *map, u32 hash)
  50 +{
  51 +       int bucket = hash & 0x3ff;
  52 +
  53 +       if (rps_table[bucket].core < 0)
  54 +               rps_table[bucket].core = rps_table_core(map);
  55 +       mod_timer(&rps_table[bucket].expire, jiffies + HZ);
  56 +
  57 +       return rps_table[bucket].core;
  58 +}
  59 +
  60 +static void rps_table_init(void)
  61 +{
  62 +       int i;
  63 +
  64 +       for (i = 0; i < RPS_TBL_SIZE; i++) {
  65 +               rps_table[i].core = -1;
  66 +               setup_timer(&rps_table[i].expire, rps_table_expire,
  67 +                           (unsigned long) &rps_table[i]);
  68 +       }
  69 +}
  70 +
  71  /*
  72   * get_rps_cpu is called from netif_receive_skb and returns the target
  73   * CPU from the RPS map of the receiving queue for a given skb.
  74 @@ -3715,7 +3767,7 @@ static int get_rps_cpu(struct net_device
  75  try_rps:
  76
  77         if (map) {
  78 -               tcpu = map->cpus[reciprocal_scale(hash, map->len)];
  79 +               tcpu = rps_table_lookup(map, hash);
  80                 if (cpu_online(tcpu)) {
  81                         cpu = tcpu;
  82                         goto done;
  83 @@ -8800,6 +8852,10 @@ static int __init net_dev_init(void)
  84                 sd->backlog.weight = weight_p;
  85         }
  86
  87 +#ifdef CONFIG_RPS
  88 +               rps_table_init();
  89 +#endif
  90 +
  91         dev_boot_phase = 0;
  92
  93         /* The loopback device is special if any other network devices