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rdma: use separate freelists for ctrl and eager rx buffers
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For default eager max size, ctrl buffers are much smaller than eager
buffers.

Signed-off-by: Eric Raut <eraut@amazon.com>
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@rauteric
rauteric committed Jan 10, 2025
1 parent ccb32bd commit ef38a5b
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Showing 2 changed files with 42 additions and 20 deletions.
12 changes: 8 additions & 4 deletions include/nccl_ofi_rdma.h
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Original file line number Diff line number Diff line change
Expand Up @@ -733,12 +733,16 @@ struct nccl_net_ofi_rdma_ep {
/* Pending requests queue */
nccl_ofi_deque_t *pending_reqs_queue;

/* Free list of rx buffers */
nccl_ofi_freelist_t *rx_buff_fl;
/* Free list of ctrl rx buffers */
nccl_ofi_freelist_t *ctrl_rx_buff_fl;
/* Free list of eager rx buffers */
nccl_ofi_freelist_t *eager_rx_buff_fl;
/* Free list of rx buffer requests */
nccl_ofi_freelist_t *rx_buff_reqs_fl;
/* Size of rx buffers */
size_t rx_buff_size;
/* Size of ctrl rx buffers */
size_t ctrl_rx_buff_size;
/* Size of eager rx buffers */
size_t eager_rx_buff_size;

/* true if the current endpoint is a endpoint_per_communicator
receive communicator */
Expand Down
50 changes: 34 additions & 16 deletions src/nccl_ofi_rdma.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2306,7 +2306,7 @@ static inline int free_eager_rx_buff_req(nccl_net_ofi_rdma_req_t *req,
nccl_net_ofi_rdma_ep_t *ep = rx_buff_data->ep;
/* Free buffer */
if (rx_buff_data->rx_buff_fl_elem) {
nccl_ofi_freelist_entry_free(ep->rx_buff_fl, rx_buff_data->rx_buff_fl_elem);
nccl_ofi_freelist_entry_free(ep->eager_rx_buff_fl, rx_buff_data->rx_buff_fl_elem);
}
return free_base_req(NULL, ep->rx_buff_reqs_fl, req, false);
}
Expand All @@ -2325,7 +2325,7 @@ static inline nccl_net_ofi_rdma_req_t *eager_rx_buff_req_alloc(nccl_net_ofi_rdma
rdma_req_rx_buff_data_t *rx_buff_data = get_rx_buff_data(req);

nccl_ofi_freelist_elem_t *rx_buff_fl_elem =
nccl_ofi_freelist_entry_alloc(ep->rx_buff_fl);
nccl_ofi_freelist_entry_alloc(ep->eager_rx_buff_fl);
if (!rx_buff_fl_elem) {
NCCL_OFI_WARN("Failed to allocate rx_buff_fl_elem");
req->free(req, false);
Expand All @@ -2334,7 +2334,7 @@ static inline nccl_net_ofi_rdma_req_t *eager_rx_buff_req_alloc(nccl_net_ofi_rdma
assert(NCCL_OFI_IS_PTR_ALIGNED(rx_buff_fl_elem->ptr, RX_BUFFER_ALIGNMENT));

rx_buff_data->rx_buff_fl_elem = rx_buff_fl_elem;
rx_buff_data->buff_len = ep->rx_buff_size;
rx_buff_data->buff_len = ep->eager_rx_buff_size;
rx_buff_data->rail = rail;
rx_buff_data->ep = ep;
return req;
Expand All @@ -2348,7 +2348,7 @@ static inline int free_ctrl_rx_buff_req(nccl_net_ofi_rdma_req_t *req,
nccl_net_ofi_rdma_ep_t *ep = rx_buff_data->ep;
/* Free buffer */
if (rx_buff_data->rx_buff_fl_elem) {
nccl_ofi_freelist_entry_free(ep->rx_buff_fl, rx_buff_data->rx_buff_fl_elem);
nccl_ofi_freelist_entry_free(ep->ctrl_rx_buff_fl, rx_buff_data->rx_buff_fl_elem);
}
return free_base_req(NULL, ep->rx_buff_reqs_fl, req, false);
}
Expand All @@ -2367,16 +2367,15 @@ static inline nccl_net_ofi_rdma_req_t *ctrl_rx_buff_req_alloc(nccl_net_ofi_rdma_
rdma_req_rx_buff_data_t *rx_buff_data = get_rx_buff_data(req);

nccl_ofi_freelist_elem_t *rx_buff_fl_elem =
nccl_ofi_freelist_entry_alloc(ep->rx_buff_fl);
nccl_ofi_freelist_entry_alloc(ep->ctrl_rx_buff_fl);
if (!rx_buff_fl_elem) {
NCCL_OFI_WARN("Failed to allocate rx_buff_fl_elem");
req->free(req, false);
return NULL;
}
assert(NCCL_OFI_IS_PTR_ALIGNED(rx_buff_fl_elem->ptr, RX_BUFFER_ALIGNMENT));

rx_buff_data->rx_buff_fl_elem = rx_buff_fl_elem;
rx_buff_data->buff_len = ep->rx_buff_size;
rx_buff_data->buff_len = ep->ctrl_rx_buff_size;
rx_buff_data->rail = rail;
rx_buff_data->ep = ep;
return req;
Expand Down Expand Up @@ -5534,8 +5533,9 @@ static int post_rx_buffer(nccl_net_ofi_rdma_req_t *req,
* accessible but undefined to cover cases where the buffer
* gets re-posted */
nccl_net_ofi_rdma_ep_t *ep = rx_buff_data->ep;
nccl_ofi_freelist_entry_set_undefined(ep->rx_buff_fl,
rx_buff_fl_elem->ptr);
nccl_ofi_freelist_t *fl = (req->type == NCCL_OFI_RDMA_EAGER_RX_BUFF ?
ep->eager_rx_buff_fl : ep->ctrl_rx_buff_fl);
nccl_ofi_freelist_entry_set_undefined(fl, rx_buff_fl_elem->ptr);

iov.iov_base = rx_buff_fl_elem->ptr;
iov.iov_len = rx_buff_data->buff_len;
Expand Down Expand Up @@ -6220,17 +6220,28 @@ static inline int init_rx_buffers(nccl_net_ofi_rdma_ep_t *ep)
return ret;
}

ret = nccl_ofi_freelist_init_mr(ep->rx_buff_size,
ret = nccl_ofi_freelist_init_mr(ep->ctrl_rx_buff_size,
ofi_nccl_rdma_min_posted_rx_buffers(), 16, 0,
freelist_regmr_host_fn, freelist_deregmr_host_fn,
ep, RX_BUFFER_ALIGNMENT, &ep->rx_buff_fl);
ep, 1, &ep->ctrl_rx_buff_fl);
if (ret != 0) {
NCCL_OFI_WARN("Failed to init rx_buff_fl");
NCCL_OFI_WARN("Failed to init ctrl_rx_buff_fl");
if (nccl_ofi_freelist_fini(ep->rx_buff_reqs_fl))
NCCL_OFI_WARN("Also failed to freelist_fini rx_buff_reqs_fl");
return ret;
}

ret = nccl_ofi_freelist_init_mr(ep->eager_rx_buff_size,
ofi_nccl_rdma_min_posted_rx_buffers(), 16, 0,
freelist_regmr_host_fn, freelist_deregmr_host_fn,
ep, RX_BUFFER_ALIGNMENT, &ep->eager_rx_buff_fl);
if (ret != 0) {
NCCL_OFI_WARN("Failed to init eager_rx_buff_size");
nccl_ofi_freelist_fini(ep->ctrl_rx_buff_fl);
nccl_ofi_freelist_fini(ep->rx_buff_reqs_fl);
return ret;
}

/*
* The *_rx_buff_posted limits are used in the progress engine to
* determine if the receive queue is hydrated with sufficient buffers.
Expand Down Expand Up @@ -6280,9 +6291,15 @@ static inline int fini_rx_buffers(nccl_net_ofi_rdma_ep_t *ep)
int ret = 0;
nccl_net_ofi_ep_rail_t *rail;

ret = nccl_ofi_freelist_fini(ep->rx_buff_fl);
ret = nccl_ofi_freelist_fini(ep->ctrl_rx_buff_fl);
if (ret != 0) {
NCCL_OFI_WARN("Failed to fini ctrl_rx_buff_fl");
return ret;
}

ret = nccl_ofi_freelist_fini(ep->eager_rx_buff_fl);
if (ret != 0) {
NCCL_OFI_WARN("Failed to fini rx_buff_fl");
NCCL_OFI_WARN("Failed to fini eager_rx_buff_fl");
return ret;
}

Expand Down Expand Up @@ -7244,8 +7261,9 @@ static int nccl_net_ofi_rdma_domain_create_endpoint(nccl_net_ofi_domain_t *base_
goto error;
}

ep->rx_buff_size = NCCL_OFI_MAX(NCCL_OFI_MAX(sizeof(nccl_net_ofi_rdma_ctrl_msg_t), eager_max_size),
sizeof(nccl_ofi_rdma_connection_info_t));
ep->ctrl_rx_buff_size = NCCL_OFI_MAX(sizeof(nccl_net_ofi_rdma_ctrl_msg_t),
sizeof(nccl_ofi_rdma_connection_info_t));
ep->eager_rx_buff_size = eager_max_size;

ep->is_endpoint_per_communicator_ep = false;

Expand Down

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