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Message-Id: <1619072500-13789-1-git-send-email-hans.westgaard.ry@oracle.com>
Date: Thu, 22 Apr 2021 08:21:40 +0200
From: Hans Westgaard Ry <hans.westgaard.ry@...cle.com>
To: Tariq Toukan <tariqt@...dia.com>,
"David S. Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org
Subject: [PATCH v2 net-next] net/mlx4: Treat VFs fair when handling comm_channel_events
Handling comm_channel_event in mlx4_master_comm_channel uses a double
loop to determine which slaves have requested work. The search is
always started at lowest slave. This leads to unfairness; lower VFs
tends to be prioritized over higher VFs.
The patch uses find_next_bit to determine which slaves to handle.
Fairness is implemented by always starting at the next to the last
start.
An MPI program has been used to measure improvements. It runs 500
ibv_reg_mr, synchronizes with all other instances and then runs 500
ibv_dereg_mr.
The results running 500 processes, time reported is for running 500
calls:
ibv_reg_mr:
Mod. Org.
mlx4_1 403.356ms 424.674ms
mlx4_2 403.355ms 424.674ms
mlx4_3 403.354ms 424.674ms
mlx4_4 403.355ms 424.674ms
mlx4_5 403.357ms 424.677ms
mlx4_6 403.354ms 424.676ms
mlx4_7 403.357ms 424.675ms
mlx4_8 403.355ms 424.675ms
ibv_dereg_mr:
Mod. Org.
mlx4_1 116.408ms 142.818ms
mlx4_2 116.434ms 142.793ms
mlx4_3 116.488ms 143.247ms
mlx4_4 116.679ms 143.230ms
mlx4_5 112.017ms 107.204ms
mlx4_6 112.032ms 107.516ms
mlx4_7 112.083ms 184.195ms
mlx4_8 115.089ms 190.618ms
Suggested-by: Håkon Bugge <haakon.bugge@...cle.com>
Signed-off-by: Hans Westgaard Ry <hans.westgaard.ry@...cle.com>
---
v1 -> v2:
- removed set but not user varible,
reported by 'kernel test robot'
- fixed reversed Christmas tree,
removed else,
removed extra varibles in printout,
moved next_slave to struct mlx4_mfunc_master_ctx,
as suggested by Tariq Toukan
drivers/net/ethernet/mellanox/mlx4/cmd.c | 69 ++++++++++++++++++-------------
drivers/net/ethernet/mellanox/mlx4/mlx4.h | 1 +
2 files changed, 41 insertions(+), 29 deletions(-)
diff --git a/drivers/net/ethernet/mellanox/mlx4/cmd.c b/drivers/net/ethernet/mellanox/mlx4/cmd.c
index c678344d22a2..8d751383530b 100644
--- a/drivers/net/ethernet/mellanox/mlx4/cmd.c
+++ b/drivers/net/ethernet/mellanox/mlx4/cmd.c
@@ -2241,43 +2241,52 @@ void mlx4_master_comm_channel(struct work_struct *work)
struct mlx4_priv *priv =
container_of(mfunc, struct mlx4_priv, mfunc);
struct mlx4_dev *dev = &priv->dev;
- __be32 *bit_vec;
+ u32 lbit_vec[COMM_CHANNEL_BIT_ARRAY_SIZE];
+ u32 nmbr_bits;
u32 comm_cmd;
- u32 vec;
- int i, j, slave;
+ int i, slave;
int toggle;
+ bool first = true;
int served = 0;
int reported = 0;
u32 slt;
- bit_vec = master->comm_arm_bit_vector;
- for (i = 0; i < COMM_CHANNEL_BIT_ARRAY_SIZE; i++) {
- vec = be32_to_cpu(bit_vec[i]);
- for (j = 0; j < 32; j++) {
- if (!(vec & (1 << j)))
- continue;
- ++reported;
- slave = (i * 32) + j;
- comm_cmd = swab32(readl(
- &mfunc->comm[slave].slave_write));
- slt = swab32(readl(&mfunc->comm[slave].slave_read))
- >> 31;
- toggle = comm_cmd >> 31;
- if (toggle != slt) {
- if (master->slave_state[slave].comm_toggle
- != slt) {
- pr_info("slave %d out of sync. read toggle %d, state toggle %d. Resynching.\n",
- slave, slt,
- master->slave_state[slave].comm_toggle);
- master->slave_state[slave].comm_toggle =
- slt;
- }
- mlx4_master_do_cmd(dev, slave,
- comm_cmd >> 16 & 0xff,
- comm_cmd & 0xffff, toggle);
- ++served;
+ for (i = 0; i < COMM_CHANNEL_BIT_ARRAY_SIZE; i++)
+ lbit_vec[i] = be32_to_cpu(master->comm_arm_bit_vector[i]);
+ nmbr_bits = dev->persist->num_vfs + 1;
+ if (++master->next_slave >= nmbr_bits)
+ master->next_slave = 0;
+ slave = master->next_slave;
+ while (true) {
+ slave = find_next_bit((const unsigned long *)&lbit_vec, nmbr_bits, slave);
+ if (!first && slave >= master->next_slave)
+ break;
+ if (slave == nmbr_bits) {
+ if (!first)
+ break;
+ first = false;
+ slave = 0;
+ continue;
+ }
+ ++reported;
+ comm_cmd = swab32(readl(&mfunc->comm[slave].slave_write));
+ slt = swab32(readl(&mfunc->comm[slave].slave_read)) >> 31;
+ toggle = comm_cmd >> 31;
+ if (toggle != slt) {
+ if (master->slave_state[slave].comm_toggle
+ != slt) {
+ pr_info("slave %d out of sync. read toggle %d, state toggle %d. Resynching.\n",
+ slave, slt,
+ master->slave_state[slave].comm_toggle);
+ master->slave_state[slave].comm_toggle =
+ slt;
}
+ mlx4_master_do_cmd(dev, slave,
+ comm_cmd >> 16 & 0xff,
+ comm_cmd & 0xffff, toggle);
+ ++served;
}
+ slave++;
}
if (reported && reported != served)
@@ -2389,6 +2398,8 @@ int mlx4_multi_func_init(struct mlx4_dev *dev)
if (!priv->mfunc.master.vf_oper)
goto err_comm_oper;
+ priv->mfunc.master.next_slave = 0;
+
for (i = 0; i < dev->num_slaves; ++i) {
vf_admin = &priv->mfunc.master.vf_admin[i];
vf_oper = &priv->mfunc.master.vf_oper[i];
diff --git a/drivers/net/ethernet/mellanox/mlx4/mlx4.h b/drivers/net/ethernet/mellanox/mlx4/mlx4.h
index 64bed7ac3836..6ccf340660d9 100644
--- a/drivers/net/ethernet/mellanox/mlx4/mlx4.h
+++ b/drivers/net/ethernet/mellanox/mlx4/mlx4.h
@@ -603,6 +603,7 @@ struct mlx4_mfunc_master_ctx {
struct mlx4_slave_event_eq slave_eq;
struct mutex gen_eqe_mutex[MLX4_MFUNC_MAX];
struct mlx4_qos_manager qos_ctl[MLX4_MAX_PORTS + 1];
+ u32 next_slave; /* mlx4_master_comm_channel */
};
struct mlx4_mfunc {
--
1.8.3.1
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