7af1fb9faa
By default the RPS delegation will happen by masking the last few bits of skb->hash. This patch adds an inermediate hash bucket that maps the masked hash to a RPS core. This makes RPS results much more deterministic on SMP systems. Signed-off-by: John Crispin <john@phrozen.org>
93 lines
2.3 KiB
Diff
93 lines
2.3 KiB
Diff
From 3e969c9695b45e1a052d43b367096ec99f2f0aac Mon Sep 17 00:00:00 2001
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From: John Crispin <john@phrozen.org>
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Date: Thu, 10 Aug 2017 15:58:29 +0200
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Subject: [PATCH] net: core: add RPS balancer
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This patch adds a hash bucket based rps hash balancer.
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Signed-off-by: John Crispin <john@phrozen.org>
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---
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net/core/dev.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
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1 file changed, 56 insertions(+), 1 deletion(-)
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--- a/net/core/dev.c
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+++ b/net/core/dev.c
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@@ -3626,6 +3626,58 @@ set_rps_cpu(struct net_device *dev, stru
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return rflow;
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}
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+#define RPS_TBL_SIZE_SHIFT 10
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+#define RPS_TBL_SIZE (1 << RPS_TBL_SIZE_SHIFT)
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+struct rps_table {
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+ int core;
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+ struct timer_list expire;
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+};
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+static struct rps_table rps_table[RPS_TBL_SIZE];
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+static int rps_table_last_core;
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+
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+static void rps_table_expire(unsigned long data)
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+{
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+ struct rps_table *entry = (struct rps_table *) data;
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+
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+ entry->core = -1;
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+}
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+
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+static int rps_table_core(struct rps_map *map)
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+{
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+ int i;
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+
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+ for (i = 0; i < map->len; i++) {
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+ int cpu = map->cpus[(rps_table_last_core + i + 1) % map->len];
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+ if (cpu_online(cpu)) {
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+ rps_table_last_core = cpu;
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+ return cpu;
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+ }
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+ }
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+ return map->cpus[0];
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+}
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+
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+static int rps_table_lookup(struct rps_map *map, u32 hash)
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+{
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+ int bucket = hash & 0x3ff;
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+
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+ if (rps_table[bucket].core < 0)
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+ rps_table[bucket].core = rps_table_core(map);
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+ mod_timer(&rps_table[bucket].expire, jiffies + HZ);
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+
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+ return rps_table[bucket].core;
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+}
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+
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+static void rps_table_init(void)
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+{
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+ int i;
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+
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+ for (i = 0; i < RPS_TBL_SIZE; i++) {
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+ rps_table[i].core = -1;
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+ setup_timer(&rps_table[i].expire, rps_table_expire,
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+ (unsigned long) &rps_table[i]);
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+ }
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+}
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+
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/*
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* get_rps_cpu is called from netif_receive_skb and returns the target
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* CPU from the RPS map of the receiving queue for a given skb.
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@@ -3715,7 +3767,7 @@ static int get_rps_cpu(struct net_device
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try_rps:
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if (map) {
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- tcpu = map->cpus[reciprocal_scale(hash, map->len)];
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+ tcpu = rps_table_lookup(map, hash);
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if (cpu_online(tcpu)) {
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cpu = tcpu;
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goto done;
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@@ -8800,6 +8852,10 @@ static int __init net_dev_init(void)
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sd->backlog.weight = weight_p;
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}
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+#ifdef CONFIG_RPS
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+ rps_table_init();
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+#endif
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+
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dev_boot_phase = 0;
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/* The loopback device is special if any other network devices
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