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authorTal Gilboa <talgi@mellanox.com>2017-05-15 14:13:16 +0300
committerSaeed Mahameed <saeedm@mellanox.com>2017-06-11 13:10:36 +0300
commitc3164d2fc48fd4fa0477ab658b644559c3fe9073 (patch)
treecc73863d662e8e8063977c3d0c6e60109c19e588 /drivers/net
parentf729860a177d097ac44321fb2f7d927a0c54c5a3 (diff)
net/mlx5e: Added BW check for DIM decision mechanism
DIM (Dynamically-tuned Interrupt Moderation) is a mechanism designed for changing the channel interrupt moderation values in order to reduce CPU overhead for all traffic types. Until now only interrupt and packet rate were sampled. We found a scenario on which we get a false indication since a change in DIM caused more aggregation and reduced packet rate while increasing BW. We now regard a change as succesfull iff: current_BW > (prev_BW + threshold) or current_BW ~= prev_BW and current_PR > (prev_PR + threshold) or current_BW ~= prev_BW and current_PR ~= prev_PR and current_IR < (prev_IR - threshold) Where BW = Bandwidth, PR = Packet rate and IR = Interrupt rate Improvements (ConnectX-4Lx 25GbE, single RX queue, LRO off) -------------------------------------------------- packet size | before[Mb/s] | after[Mb/s] | gain | 2B | 343.4 | 359.4 | 4.5% | 16B | 2739.7 | 2814.8 | 2.7% | 64B | 9739 | 10185.3 | 4.5% | Fixes: cb3c7fd4f839 ("net/mlx5e: Support adaptive RX coalescing") Signed-off-by: Tal Gilboa <talgi@mellanox.com> Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Diffstat (limited to 'drivers/net')
-rw-r--r--drivers/net/ethernet/mellanox/mlx5/core/en.h2
-rw-r--r--drivers/net/ethernet/mellanox/mlx5/core/en_rx_am.c37
2 files changed, 22 insertions, 17 deletions
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en.h b/drivers/net/ethernet/mellanox/mlx5/core/en.h
index 2fd044b23875..429da21a583d 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en.h
@@ -458,12 +458,14 @@ struct mlx5e_mpw_info {
struct mlx5e_rx_am_stats {
int ppms; /* packets per msec */
+ int bpms; /* bytes per msec */
int epms; /* events per msec */
};
struct mlx5e_rx_am_sample {
ktime_t time;
unsigned int pkt_ctr;
+ unsigned int byte_ctr;
u16 event_ctr;
};
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rx_am.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rx_am.c
index 02dd3a95ed8f..54cdda957f9a 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx_am.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx_am.c
@@ -183,28 +183,27 @@ static void mlx5e_am_exit_parking(struct mlx5e_rx_am *am)
mlx5e_am_step(am);
}
+#define IS_SIGNIFICANT_DIFF(val, ref) \
+ (((100 * abs((val) - (ref))) / (ref)) > 10) /* more than 10% difference */
+
static int mlx5e_am_stats_compare(struct mlx5e_rx_am_stats *curr,
struct mlx5e_rx_am_stats *prev)
{
- int diff;
-
- if (!prev->ppms)
- return curr->ppms ? MLX5E_AM_STATS_BETTER :
+ if (!prev->bpms)
+ return curr->bpms ? MLX5E_AM_STATS_BETTER :
MLX5E_AM_STATS_SAME;
- diff = curr->ppms - prev->ppms;
- if (((100 * abs(diff)) / prev->ppms) > 10) /* more than 10% diff */
- return (diff > 0) ? MLX5E_AM_STATS_BETTER :
- MLX5E_AM_STATS_WORSE;
+ if (IS_SIGNIFICANT_DIFF(curr->bpms, prev->bpms))
+ return (curr->bpms > prev->bpms) ? MLX5E_AM_STATS_BETTER :
+ MLX5E_AM_STATS_WORSE;
- if (!prev->epms)
- return curr->epms ? MLX5E_AM_STATS_WORSE :
- MLX5E_AM_STATS_SAME;
+ if (IS_SIGNIFICANT_DIFF(curr->ppms, prev->ppms))
+ return (curr->ppms > prev->ppms) ? MLX5E_AM_STATS_BETTER :
+ MLX5E_AM_STATS_WORSE;
- diff = curr->epms - prev->epms;
- if (((100 * abs(diff)) / prev->epms) > 10) /* more than 10% diff */
- return (diff < 0) ? MLX5E_AM_STATS_BETTER :
- MLX5E_AM_STATS_WORSE;
+ if (IS_SIGNIFICANT_DIFF(curr->epms, prev->epms))
+ return (curr->epms < prev->epms) ? MLX5E_AM_STATS_BETTER :
+ MLX5E_AM_STATS_WORSE;
return MLX5E_AM_STATS_SAME;
}
@@ -266,6 +265,7 @@ static void mlx5e_am_sample(struct mlx5e_rq *rq,
{
s->time = ktime_get();
s->pkt_ctr = rq->stats.packets;
+ s->byte_ctr = rq->stats.bytes;
s->event_ctr = rq->cq.event_ctr;
}
@@ -278,12 +278,15 @@ static void mlx5e_am_calc_stats(struct mlx5e_rx_am_sample *start,
/* u32 holds up to 71 minutes, should be enough */
u32 delta_us = ktime_us_delta(end->time, start->time);
unsigned int npkts = end->pkt_ctr - start->pkt_ctr;
+ unsigned int nbytes = end->byte_ctr - start->byte_ctr;
if (!delta_us)
return;
- curr_stats->ppms = (npkts * USEC_PER_MSEC) / delta_us;
- curr_stats->epms = (MLX5E_AM_NEVENTS * USEC_PER_MSEC) / delta_us;
+ 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(MLX5E_AM_NEVENTS * USEC_PER_MSEC,
+ delta_us);
}
void mlx5e_rx_am_work(struct work_struct *work)