[PAL] Add barex transport adaptor

[ymmyys]

PR Category

PAL

PR Types

New Features

PR Description

This PR adds a Barex transport adapter to FlagCX and integrates it with PPU ACCL.

[CLAassistant]

All committers have signed the CLA.

[Copilot]

Pull request overview

This PR introduces an ACCL (accl::barex) transport path to FlagCX, adding both a new net adaptor (“BAREX”) and a P2P-engine transport option selected via FLAGCX_P2P_TRANSPORT=accl, targeting PPU + vsolar environments where peer-mem/DMA-BUF isn’t available.

Changes:

• Add USE_ACCL_BAREX build option and link/include integration for libaccl_barex.
• Add ACCL P2P transport implementation (flagcx_p2p_accl.*) and dispatch routing in flagcx_p2p.cc via kind tags.
• Add barex net adaptor implementation and wire it into unified net adaptor selection when enabled.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
Makefile	Adds USE_ACCL_BAREX build toggle and injects ACCL include/link flags into compile/link steps.
flagcx/core/include/flagcx_p2p_accl.h	Declares ACCL P2P transport interface + kind-tag routing helper/stubs.
flagcx/core/flagcx_p2p.cc	Routes public P2P API entry points to ACCL transport based on runtime selection and kind tags.
flagcx/core/flagcx_p2p_accl.cc	Implements ACCL-based P2P engine/connection, registration, RDMA ops, metadata, and notif plumbing.
flagcx/adaptor/net/barex_adaptor.cc	Implements BAREX net adaptor over ACCL barex (listen/connect/accept, MR reg, isend/irecv/test).
flagcx/adaptor/adaptor.cc	Selects flagcxNetBarex as the unified IBRC adaptor when USE_ACCL_BAREX is enabled.

Suppressed comments (3)

flagcx/adaptor/net/barex_adaptor.cc:641

• If HELLO buffer allocation fails after creating/inserting a BarexComm, the code deletes connectState but leaks the BarexComm and leaves the XChannel registered in channelComm. It also leaves handle->state in BAREX_CONN_CONNECTING, preventing retries.

    if (e->mempool->AllocBuffer(msg, sizeof(BarexHelloMsg), accl::barex::CPU,
                                ch->GetLocalNicId(),
                                0) != accl::barex::BAREX_SUCCESS) {
      WARN("NET/BAREX : HELLO buffer alloc failed");
      delete st;

flagcx/adaptor/net/barex_adaptor.cc:666

• If HELLO send fails synchronously, barexConnect deletes connectState but leaks the BarexComm/channel mapping and keeps handle->state at BAREX_CONN_CONNECTING. This can leak resources and makes retries impossible.

    if (r != accl::barex::BAREX_SUCCESS) {
      WARN("NET/BAREX : HELLO send sync error: %s", bxstr(r));
      /* per xchannel.h: on send failure the buffer is NOT auto-released */
      e->mempool->ReleaseBuffer(msg.buf, accl::barex::CPU);
      delete st;

flagcx/adaptor/net/barex_adaptor.cc:678

• If HELLO delivery fails asynchronously (helloFailed), barexConnect deletes connectState but leaves the created BarexComm/XChannel in channelComm and does not reset handle->state. This leaks resources and prevents recovery.

  /* BAREX_CONN_HELLO */
  if (st->helloFailed.load(std::memory_order_acquire)) {
    WARN("NET/BAREX : HELLO delivery failed");
    delete st;
    handle->connectState = nullptr;

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[Copilot]

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated 1 comment.