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[vLLM] UCX plugin: defer packRkey to prevent GPU memory pin on ROCm #28

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AndreasKaratzas wants to merge 1 commit into from
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[vLLM] UCX plugin: defer packRkey to prevent GPU memory pin on ROCm #28

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22 changes: 16 additions & 6 deletions src/plugins/ucx/ucx_backend.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1239,11 +1239,9 @@ nixl_status_t nixlUcxEngine::registerMem (const nixlBlobDesc &mem,
if (ret) {
return NIXL_ERR_BACKEND;
}
priv->rkeyStr = uc->packRkey(priv->mem);

if (priv->rkeyStr.empty()) {
return NIXL_ERR_BACKEND;
}
// Defer packRkey to getPublicData/loadLocalMD. Packing eagerly here
// triggers hsa_amd_ipc_memory_create (via ucp_rkey_pack) which
// permanently pins GPU memory on ROCm with no release API.
out = priv.release();
return NIXL_SUCCESS;
}
Expand All @@ -1258,7 +1256,13 @@ nixl_status_t nixlUcxEngine::deregisterMem (nixlBackendMD* meta)

nixl_status_t nixlUcxEngine::getPublicData (const nixlBackendMD* meta,
std::string &str) const {
const nixlUcxPrivateMetadata *priv = (nixlUcxPrivateMetadata*) meta;
const nixlUcxPrivateMetadata *priv = (const nixlUcxPrivateMetadata *)meta;
if (priv->rkeyStr.empty()) {
priv->rkeyStr = uc->packRkey(priv->mem);
if (priv->rkeyStr.empty()) {
return NIXL_ERR_BACKEND;
}
}
str = priv->get();
return NIXL_SUCCESS;
}
Expand Down Expand Up @@ -1303,6 +1307,12 @@ nixlUcxEngine::loadLocalMD (nixlBackendMD* input,
nixlBackendMD* &output)
{
nixlUcxPrivateMetadata* input_md = (nixlUcxPrivateMetadata*) input;
if (input_md->rkeyStr.empty()) {
input_md->rkeyStr = uc->packRkey(input_md->mem);
if (input_md->rkeyStr.empty()) {
return NIXL_ERR_BACKEND;
}
}
return internalMDHelper(input_md->rkeyStr, localAgent, output);
}

Expand Down
4 changes: 2 additions & 2 deletions src/plugins/ucx/ucx_backend.h
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Expand Up @@ -58,8 +58,8 @@ using ucx_connection_ptr_t = std::shared_ptr<nixlUcxConnection>;
// A private metadata has to implement get, and has all the metadata
class nixlUcxPrivateMetadata : public nixlBackendMD {
private:
nixlUcxMem mem;
nixl_blob_t rkeyStr;
mutable nixlUcxMem mem;
mutable nixl_blob_t rkeyStr;

public:
nixlUcxPrivateMetadata() : nixlBackendMD(true) {
Expand Down
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