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Enable libfabric backend plugin with CXI provider for Slingshot network #1057

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Enable libfabric backend plugin with CXI provider for Slingshot network #1057

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7 changes: 6 additions & 1 deletion src/utils/libfabric/libfabric_common.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -50,6 +50,9 @@ getAvailableNetworkDevices() {
hints->mode = FI_CONTEXT;
hints->ep_attr->type = FI_EP_RDM;

// Add CXI-compatible memory registration mode
hints->domain_attr->mr_mode = FI_MR_LOCAL | FI_MR_ENDPOINT | FI_MR_ALLOCATED | FI_MR_PROV_KEY;

int ret = fi_getinfo(FI_VERSION(1, 18), NULL, NULL, 0, hints, &info);
if (ret) {
NIXL_ERROR << "fi_getinfo failed " << fi_strerror(-ret);
Expand Down Expand Up @@ -85,7 +88,9 @@ getAvailableNetworkDevices() {
}
}

if (provider_device_map.find("efa") != provider_device_map.end()) {
if (provider_device_map.find("cxi") != provider_device_map.end()) {
return {"cxi", provider_device_map["cxi"]};
} else if (provider_device_map.find("efa") != provider_device_map.end()) {
return {"efa", provider_device_map["efa"]};
} else if (provider_device_map.find("sockets") != provider_device_map.end()) {
return {"sockets", {provider_device_map["sockets"][0]}};
Expand Down
34 changes: 32 additions & 2 deletions src/utils/libfabric/libfabric_rail.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -421,10 +421,16 @@ nixlLibfabricRail::nixlLibfabricRail(const std::string &device,
// TCP provider doesn't support FI_MR_PROV_KEY or FI_MR_VIRT_ADDR, use basic mode
hints->domain_attr->mr_mode = FI_MR_LOCAL | FI_MR_ALLOCATED;
hints->domain_attr->mr_key_size = 0; // Let provider decide
} else if (provider == "cxi") {
hints->caps |= FI_RMA_EVENT;
hints->domain_attr->mr_mode =
FI_MR_LOCAL | FI_MR_HMEM | FI_MR_VIRT_ADDR |
FI_MR_ALLOCATED | FI_MR_PROV_KEY | FI_MR_ENDPOINT;
} else {
// EFA and other providers support advanced memory registration
hints->domain_attr->mr_mode =
FI_MR_LOCAL | FI_MR_HMEM | FI_MR_VIRT_ADDR | FI_MR_ALLOCATED | FI_MR_PROV_KEY;
FI_MR_LOCAL | FI_MR_HMEM | FI_MR_VIRT_ADDR |
FI_MR_ALLOCATED | FI_MR_PROV_KEY;
hints->domain_attr->mr_key_size = 2;
}
hints->domain_attr->name = strdup(device_name.c_str());
Expand Down Expand Up @@ -1347,8 +1353,14 @@ nixlLibfabricRail::registerMemory(void *buffer,
iov.iov_len = length;
mr_attr.mr_iov = &iov;
mr_attr.iov_count = 1;
int ret = 0;

if (provider_name == "cxi") {
ret = fi_mr_regattr(domain, &mr_attr, FI_RMA_EVENT, &mr);
} else {
ret = fi_mr_regattr(domain, &mr_attr, 0, &mr);
}

int ret = fi_mr_regattr(domain, &mr_attr, 0, &mr);
if (ret) {
NIXL_ERROR << "fi_mr_reg failed on rail " << rail_id << ": " << fi_strerror(-ret)
<< " (buffer=" << buffer << ", length=" << length
Expand All @@ -1357,6 +1369,24 @@ nixlLibfabricRail::registerMemory(void *buffer,
}

*mr_out = mr;

if (info->domain_attr->mr_mode & FI_MR_ENDPOINT) {
ret = fi_mr_bind(mr, &endpoint->fid, 0);
if (ret) {
NIXL_ERROR << "fi_mr_bind failed on rail " << rail_id << ": " << fi_strerror(-ret);
fi_close(&mr->fid);
return NIXL_ERR_BACKEND;
}

ret = fi_mr_enable(mr);
if (ret) {
NIXL_ERROR << "fi_mr_enable failed on rail " << rail_id << ": " << fi_strerror(-ret);
fi_close(&mr->fid);
return NIXL_ERR_BACKEND;
}
}


*key_out = fi_mr_key(mr);

NIXL_TRACE << "Memory Registration SUCCESS: rail=" << rail_id << " provider=" << provider_name
Expand Down
6 changes: 4 additions & 2 deletions src/utils/libfabric/libfabric_rail_manager.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -179,7 +179,8 @@ nixlLibfabricRailManager::prepareAndSubmitTransfer(

// For TCP providers, use offset 0 instead of virtual address
// TCP providers don't support FI_MR_VIRT_ADDR and expect offset-based addressing
if (data_rails_[rail_id]->provider_name == "tcp" ||
if (data_rails_[rail_id]->provider_name == "cxi" ||
data_rails_[rail_id]->provider_name == "tcp" ||
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@sielicki sielicki Nov 25, 2025

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@akkart-aws was there a reason you couldn't just check for FI_MR_VIRT_ADDR directly here?

data_rails_[rail_id]->provider_name == "sockets") {
req->remote_addr = 0; // Use offset 0 for TCP providers
NIXL_DEBUG << "TCP provider detected: using offset 0 instead of virtual address "
Expand Down Expand Up @@ -258,7 +259,8 @@ nixlLibfabricRailManager::prepareAndSubmitTransfer(

// For TCP providers, use offset instead of virtual address
// TCP providers don't support FI_MR_VIRT_ADDR and expect offset-based addressing
if (data_rails_[rail_id]->provider_name == "tcp" ||
if (data_rails_[rail_id]->provider_name == "cxi" ||
data_rails_[rail_id]->provider_name == "tcp" ||
data_rails_[rail_id]->provider_name == "sockets") {
req->remote_addr = chunk_offset; // Use chunk offset for TCP providers
NIXL_DEBUG << "TCP provider detected: using chunk offset " << chunk_offset
Expand Down
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