linux/dim: Move logic to dim.h

In preparation for supporting more implementations of the DIM
algorithm, I'm moving what would become common logic to a common
library. Downstream DIM implementations will use the common lib
for their implementation.

Signed-off-by: Tal Gilboa <talgi@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

1 files changed, 153 insertions, 0 deletions

diff --git a/include/linux/dim.h b/include/linux/dim.h
new file mode 100644
index 000000000000..67d7ca40f3dd
--- /dev/null
+++ b/include/linux/dim.h
@@ -0,0 +1,153 @@
+/* SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB */
+/* Copyright (c) 2019 Mellanox Technologies. */
+
+#ifndef DIM_H
+#define DIM_H
+
+#include <linux/module.h>
+
+#define NET_DIM_NEVENTS 64
+
+/* more than 10% difference */
+#define IS_SIGNIFICANT_DIFF(val, ref) \
+	(((100UL * abs((val) - (ref))) / (ref)) > 10)
+#define BIT_GAP(bits, end, start) ((((end) - (start)) + BIT_ULL(bits)) \
+& (BIT_ULL(bits) - 1))
+
+struct net_dim_cq_moder {
+	u16 usec;
+	u16 pkts;
+	u8 cq_period_mode;
+};
+
+struct net_dim_sample {
+	ktime_t time;
+	u32 pkt_ctr;
+	u32 byte_ctr;
+	u16 event_ctr;
+};
+
+struct net_dim_stats {
+	int ppms; /* packets per msec */
+	int bpms; /* bytes per msec */
+	int epms; /* events per msec */
+};
+
+struct net_dim { /* Dynamic Interrupt Moderation */
+	u8 state;
+	struct net_dim_stats prev_stats;
+	struct net_dim_sample start_sample;
+	struct work_struct work;
+	u8 profile_ix;
+	u8 mode;
+	u8 tune_state;
+	u8 steps_right;
+	u8 steps_left;
+	u8 tired;
+};
+
+enum {
+	NET_DIM_CQ_PERIOD_MODE_START_FROM_EQE = 0x0,
+	NET_DIM_CQ_PERIOD_MODE_START_FROM_CQE = 0x1,
+	NET_DIM_CQ_PERIOD_NUM_MODES
+};
+
+enum {
+	NET_DIM_START_MEASURE,
+	NET_DIM_MEASURE_IN_PROGRESS,
+	NET_DIM_APPLY_NEW_PROFILE,
+};
+
+enum {
+	NET_DIM_PARKING_ON_TOP,
+	NET_DIM_PARKING_TIRED,
+	NET_DIM_GOING_RIGHT,
+	NET_DIM_GOING_LEFT,
+};
+
+enum {
+	NET_DIM_STATS_WORSE,
+	NET_DIM_STATS_SAME,
+	NET_DIM_STATS_BETTER,
+};
+
+enum {
+	NET_DIM_STEPPED,
+	NET_DIM_TOO_TIRED,
+	NET_DIM_ON_EDGE,
+};
+
+static inline bool net_dim_on_top(struct net_dim *net_dim)
+{
+	switch (net_dim->tune_state) {
+	case NET_DIM_PARKING_ON_TOP:
+	case NET_DIM_PARKING_TIRED:
+		return true;
+	case NET_DIM_GOING_RIGHT:
+		return (net_dim->steps_left > 1) && (net_dim->steps_right == 1);
+	default: /* NET_DIM_GOING_LEFT */
+		return (net_dim->steps_right > 1) && (net_dim->steps_left == 1);
+	}
+}
+
+static inline void net_dim_turn(struct net_dim *net_dim)
+{
+	switch (net_dim->tune_state) {
+	case NET_DIM_PARKING_ON_TOP:
+	case NET_DIM_PARKING_TIRED:
+		break;
+	case NET_DIM_GOING_RIGHT:
+		net_dim->tune_state = NET_DIM_GOING_LEFT;
+		net_dim->steps_left = 0;
+		break;
+	case NET_DIM_GOING_LEFT:
+		net_dim->tune_state = NET_DIM_GOING_RIGHT;
+		net_dim->steps_right = 0;
+		break;
+	}
+}
+
+static inline void net_dim_park_on_top(struct net_dim *net_dim)
+{
+	net_dim->steps_right  = 0;
+	net_dim->steps_left   = 0;
+	net_dim->tired        = 0;
+	net_dim->tune_state   = NET_DIM_PARKING_ON_TOP;
+}
+
+static inline void net_dim_park_tired(struct net_dim *net_dim)
+{
+	net_dim->steps_right  = 0;
+	net_dim->steps_left   = 0;
+	net_dim->tune_state   = NET_DIM_PARKING_TIRED;
+}
+
+static inline void
+net_dim_sample(u16 event_ctr, u64 packets, u64 bytes, struct net_dim_sample *s)
+{
+	s->time	     = ktime_get();
+	s->pkt_ctr   = packets;
+	s->byte_ctr  = bytes;
+	s->event_ctr = event_ctr;
+}
+
+static inline void
+net_dim_calc_stats(struct net_dim_sample *start, struct net_dim_sample *end,
+		   struct net_dim_stats *curr_stats)
+{
+	/* u32 holds up to 71 minutes, should be enough */
+	u32 delta_us = ktime_us_delta(end->time, start->time);
+	u32 npkts = BIT_GAP(BITS_PER_TYPE(u32), end->pkt_ctr, start->pkt_ctr);
+	u32 nbytes = BIT_GAP(BITS_PER_TYPE(u32), end->byte_ctr,
+			     start->byte_ctr);
+
+	if (!delta_us)
+		return;
+
+	curr_stats->ppms = DIV_ROUND_UP(npkts * USEC_PER_MSEC, delta_us);
+	curr_stats->bpms = DIV_ROUND_UP(nbytes * USEC_PER_MSEC, delta_us);
+	curr_stats->epms = DIV_ROUND_UP(NET_DIM_NEVENTS * USEC_PER_MSEC,
+					delta_us);
+}
+
+#endif /* DIM_H */