Remove ncclConfig_t bindings

zdevito · zdevito · commit eb3249026069 · 2025-12-08T12:20:06.000-08:00
Pull Request resolved: #2086 These were never used but complicate how we have to generate bindings to nccl. ghstack-source-id: 327879735 @exported-using-ghexport Differential Revision: [D88656649](https://our.internmc.facebook.com/intern/diff/D88656649/)
diff --git a/monarch_extension/src/convert.rs b/monarch_extension/src/convert.rs
@@ -355,14 +355,12 @@ fn create_map(py: Python) -> HashMap<u64, FnType> {
             dims: p.parse("dims")?,
             device_mesh: p.parseRef("device_mesh")?,
             stream: p.parseStreamRef("stream")?,
-            config: None,
         })
     });
     m.insert(key("SplitCommForProcessGroup"), |p| {
         Ok(WorkerMessage::SplitCommForProcessGroup {
             remote_process_group: p.parseRef("remote_process_group")?,
             stream: p.parseStreamRef("stream")?,
-            config: None,
         })
     });
     m.insert(key("DefineRecording"), |p| {
diff --git a/monarch_messages/src/worker.rs b/monarch_messages/src/worker.rs
@@ -38,7 +38,6 @@ use pyo3::types::PyTuple;
 use serde::Deserialize;
 use serde::Serialize;
 use thiserror::Error;
-use torch_sys_cuda::nccl::NcclConfig;
 use torch_sys_cuda::nccl::ReduceOp;
 use torch_sys_cuda::nccl::UniqueId;
 use torch_sys2::BorrowError;
@@ -800,10 +799,6 @@ pub enum WorkerMessage {
         /// will be ordered with respect to other operations scheduled on this
         /// stream.
         stream: StreamRef,
-        /// Configuration for the new communicator. If None, we will not pass a
-        /// config object to nccl, which means that the created communicator
-        /// will inherit its parent's config.
-        config: Option<NcclConfig>,
     },
 
     /// Create a new communicator on each rank in `ranks`, capable of
@@ -816,10 +811,6 @@ pub enum WorkerMessage {
         /// will be ordered with respect to other operations scheduled on this
         /// stream.
         stream: StreamRef,
-        /// Configuration for the new communicator. If None, we will not pass a
-        /// config object to nccl, which means that the created communicator
-        /// will inherit its parent's config.
-        config: Option<NcclConfig>,
     },
 
     SendTensor {
diff --git a/monarch_tensor_worker/src/comm.rs b/monarch_tensor_worker/src/comm.rs
@@ -25,7 +25,6 @@ use tokio::task::spawn_blocking;
 use torch_sys_cuda::cuda::Event;
 use torch_sys_cuda::cuda::Stream;
 use torch_sys_cuda::nccl::Communicator;
-use torch_sys_cuda::nccl::NcclConfig;
 use torch_sys_cuda::nccl::NcclError;
 use torch_sys_cuda::nccl::NcclStatus;
 use torch_sys_cuda::nccl::ReduceOp;
@@ -90,14 +89,10 @@ pub enum CommMessage {
 
     Group(Vec<CommMessage>, Stream, #[reply] OncePortHandle<Event>),
 
-    SplitAll(
-        Option<NcclConfig>,
-        #[reply] OncePortHandle<ActorHandle<NcclCommActor>>,
-    ),
+    SplitAll(#[reply] OncePortHandle<ActorHandle<NcclCommActor>>),
 
     SplitFrom(
         Vec<i32>,
-        Option<NcclConfig>,
         #[reply] OncePortHandle<Option<ActorHandle<NcclCommActor>>>,
     ),
 }
@@ -224,11 +219,10 @@ impl CommMessageHandler for NcclCommActor {
     async fn split_all(
         &mut self,
         cx: &hyperactor::Context<Self>,
-        nccl_config: Option<NcclConfig>,
     ) -> Result<ActorHandle<NcclCommActor>> {
         let comm = self.comm.clone();
 
-        let split_comm = spawn_blocking(move || comm.lock().split_all(nccl_config))
+        let split_comm = spawn_blocking(move || comm.lock().split_all())
             .await
             .unwrap()?;
 
@@ -241,11 +235,10 @@ impl CommMessageHandler for NcclCommActor {
         &mut self,
         cx: &hyperactor::Context<Self>,
         ranks: Vec<i32>,
-        nccl_config: Option<NcclConfig>,
     ) -> Result<Option<ActorHandle<NcclCommActor>>> {
         let comm = self.comm.clone();
 
-        let split_comm = spawn_blocking(move || comm.lock().split_from(ranks, nccl_config))
+        let split_comm = spawn_blocking(move || comm.lock().split_from(ranks))
             .await
             .unwrap()?;
 
diff --git a/monarch_tensor_worker/src/lib.rs b/monarch_tensor_worker/src/lib.rs
@@ -90,7 +90,6 @@ use sorted_vec::SortedVec;
 use stream::StreamActor;
 use stream::StreamMessageClient;
 use stream::StreamParams;
-use torch_sys_cuda::nccl::NcclConfig;
 use torch_sys_cuda::nccl::ReduceOp;
 use torch_sys_cuda::nccl::UniqueId;
 use torch_sys2::CudaDevice;
@@ -340,7 +339,7 @@ impl WorkerMessageHandler for WorkerActor {
         for _ in 0..sorted_streams.len() {
             // Do the split in this event loop, to provide a deterministic
             // order.
-            splits.push(comm.split_all(cx, None).await?);
+            splits.push(comm.split_all(cx).await?);
         }
         let _: Vec<()> = try_join_all(
             sorted_streams
@@ -371,7 +370,7 @@ impl WorkerMessageHandler for WorkerActor {
             .comm
             .as_ref()
             .context("tried to call Reduce before BackendNetworkInit")?;
-        let comm = global_comm.split_all(cx, None).await?;
+        let comm = global_comm.split_all(cx).await?;
         self.send_recv_comms
             .insert((from_stream, to_stream), Arc::new(comm));
         Ok(())
@@ -803,7 +802,6 @@ impl WorkerMessageHandler for WorkerActor {
         dims: Vec<String>,
         device_mesh: Ref,
         stream_ref: StreamRef,
-        config: Option<NcclConfig>,
     ) -> Result<()> {
         let global_comm = self
             .comm
@@ -833,7 +831,6 @@ impl WorkerMessageHandler for WorkerActor {
                             .into_iter()
                             .map(|v| v.clone().try_into())
                             .collect::<Result<Vec<_>, _>>()?,
-                        config,
                     )
                     .await?
                     .context("split comm should include self rank")?;
@@ -842,7 +839,7 @@ impl WorkerMessageHandler for WorkerActor {
             None => {
                 // This rank is not in the group to be split off. We still need to
                 // participate in the commSplit call, however.
-                global_comm.split_from(cx, vec![], config).await?;
+                global_comm.split_from(cx, vec![]).await?;
             }
         }
         Ok(())
@@ -853,7 +850,6 @@ impl WorkerMessageHandler for WorkerActor {
         cx: &hyperactor::Context<Self>,
         remote_process_group_ref: Ref,
         stream_ref: StreamRef,
-        config: Option<NcclConfig>,
     ) -> Result<()> {
         ensure!(
             self.streams.contains_key(&stream_ref),
@@ -888,7 +884,6 @@ impl WorkerMessageHandler for WorkerActor {
                             .into_iter()
                             .map(|v| v.clone().try_into())
                             .collect::<Result<Vec<_>, _>>()?,
-                        config,
                     )
                     .await?
                     .context("split comm should include self rank")?;
@@ -897,7 +892,7 @@ impl WorkerMessageHandler for WorkerActor {
             None => {
                 // This rank is not in the group to be split off. We still need to
                 // participate in the commSplit call, however.
-                global_comm.split_from(cx, vec![], config).await?;
+                global_comm.split_from(cx, vec![]).await?;
             }
         }
         Ok(())
diff --git a/nccl-sys/build.rs b/nccl-sys/build.rs
@@ -68,7 +68,6 @@ fn main() {
         .allowlist_type("ncclDataType_t")
         .allowlist_type("ncclRedOp_t")
         .allowlist_type("ncclScalarResidence_t")
-        .allowlist_type("ncclConfig_t")
         .allowlist_type("ncclSimInfo_t")
         .allowlist_var("NCCL_SPLIT_NOCOLOR")
         .allowlist_var("NCCL_MAJOR")
diff --git a/nccl-sys/src/lib.rs b/nccl-sys/src/lib.rs
@@ -15,13 +15,6 @@ unsafe impl ExternType for CUstream_st {
     type Kind = cxx::kind::Opaque;
 }
 
-/// SAFETY: bindings
-/// Trivial because this is POD struct
-unsafe impl ExternType for ncclConfig_t {
-    type Id = type_id!("ncclConfig_t");
-    type Kind = cxx::kind::Trivial;
-}
-
 /// SAFETY: bindings
 unsafe impl ExternType for ncclComm {
     type Id = type_id!("ncclComm");
diff --git a/torch-sys-cuda/src/bridge.h b/torch-sys-cuda/src/bridge.h
@@ -8,16 +8,4 @@
 
 #pragma once
 
-#include <nccl.h> // @manual
-
-namespace monarch {
-
-/// This function exists because ncclConfig initialization requires the use of
-/// a macro. We cannot reference the macro directly from Rust code, so we wrap
-/// the macro use in a function and bind that to Rust instead.
-inline ncclConfig_t make_nccl_config() {
-  ncclConfig_t ret = NCCL_CONFIG_INITIALIZER;
-  return ret;
-}
-
-} // namespace monarch
+namespace monarch {} // namespace monarch
diff --git a/torch-sys-cuda/src/bridge.rs b/torch-sys-cuda/src/bridge.rs
@@ -11,10 +11,5 @@
 pub(crate) mod ffi {
     unsafe extern "C++" {
         include!("monarch/torch-sys-cuda/src/bridge.h");
-
-        // nccl helpers
-        #[namespace = ""]
-        type ncclConfig_t = nccl_sys::ncclConfig_t;
-        fn make_nccl_config() -> ncclConfig_t;
     }
 }
diff --git a/torch-sys-cuda/src/nccl.rs b/torch-sys-cuda/src/nccl.rs
@@ -6,7 +6,6 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-use std::ffi::CString;
 use std::fmt;
 use std::fmt::Write;
 use std::hash::Hasher;
@@ -26,7 +25,6 @@ use torch_sys2::TensorCell;
 use torch_sys2::factory_float_tensor;
 use torch_sys2::is_float8_type;
 
-use crate::bridge::ffi::make_nccl_config;
 use crate::cuda::CudaError;
 use crate::cuda::Stream;
 use crate::cuda::set_device;
@@ -100,60 +98,6 @@ pub enum NcclStatus {
     InProgress,
 }
 
-/// Rust version of ncclConfig_t. See nccl documentation for what each field
-/// means:
-/// https://docs.nvidia.com/deeplearning/nccl/user-guide/docs/api/types.html#ncclconfig-t
-///
-/// Note that we don't validate field values; we rely on nccl to do that.
-#[derive(Debug, Clone, Serialize, Deserialize)]
-pub struct NcclConfig {
-    pub blocking: bool,
-    pub cga_cluster_size: u8,
-    pub min_ctas: u8,
-    pub max_ctas: u8,
-    pub net_name: Option<String>,
-    pub split_share: bool,
-}
-
-impl Default for NcclConfig {
-    fn default() -> Self {
-        NcclConfig {
-            blocking: true,
-            cga_cluster_size: 4,
-            min_ctas: 1,
-            max_ctas: 32,
-            net_name: None,
-            split_share: false,
-        }
-    }
-}
-
-impl From<NcclConfig> for ncclConfig_t {
-    fn from(config: NcclConfig) -> Self {
-        let mut ret = make_nccl_config();
-        ret.blocking = config.blocking.into();
-        ret.cgaClusterSize = config.cga_cluster_size.into();
-        ret.minCTAs = config.min_ctas.into();
-        ret.maxCTAs = config.max_ctas.into();
-        if let Some(net_name) = config.net_name {
-            let c_string = CString::new(net_name)
-                .expect("failed to create CString")
-                .into_boxed_c_str();
-
-            // Just leak the string to avoid complicated ownership issues. I'm
-            // not aware of anywhere where we actually want to specify the
-            // network module name in configuration instead of letting nccl just
-            // choose it for us. If this happens + we are creating tons of
-            // config objects, we can revisit this.
-            let ptr = Box::leak(c_string).as_ptr();
-            ret.netName = ptr;
-        }
-        ret.splitShare = config.split_share.into();
-
-        ret
-    }
-}
-
 fn nccl_check(result: ncclResult_t) -> Result<NcclStatus, RawNcclError> {
     match result.0 {
         0 => Ok(NcclStatus::Success),
@@ -383,9 +327,9 @@ impl Communicator {
 
     /// Split off a new communicator from this one, preserving the same world
     /// size.
-    pub fn split_all(&mut self, config: Option<NcclConfig>) -> Result<Self, NcclError> {
+    pub fn split_all(&mut self) -> Result<Self, NcclError> {
         let ranks = (0..self.global_world_size).collect();
-        Ok(self.split_from(ranks, config)?.unwrap())
+        Ok(self.split_from(ranks)?.unwrap())
     }
 
     /// Split off a new communicator from this one. Only `ranks` will be present
@@ -394,11 +338,7 @@ impl Communicator {
     /// If `ranks` is empty, `ncclCommSplit` will be called with
     /// NCCL_SPLIT_NOCOLOR. This can be useful if ranks excluded from the split
     /// don't even know what ranks will be included.
-    pub fn split_from(
-        &mut self,
-        mut ranks: Vec<i32>,
-        config: Option<NcclConfig>,
-    ) -> Result<Option<Self>, NcclError> {
+    pub fn split_from(&mut self, mut ranks: Vec<i32>) -> Result<Option<Self>, NcclError> {
         ranks.sort();
         for rank in &ranks {
             if *rank < 0 || *rank >= self.global_world_size {
@@ -411,34 +351,17 @@ impl Communicator {
             Err(_) => NCCL_SPLIT_NOCOLOR,
         };
 
-        let config = config.map(ncclConfig_t::from);
         let mut new = MaybeUninit::uninit();
 
         // SAFETY: intended use of C function
         let new = unsafe {
-            // This rather awkward duplication is intentional; we are passing in
-            // `config` as a pointer, which is only guaranteed to be valid for
-            // the duration of `Some(mut config)` match arm.
-            match config {
-                Some(mut config) => {
-                    nccl_check(ncclCommSplit(
-                        self.inner,
-                        color,
-                        self.rank,
-                        new.as_mut_ptr(),
-                        &mut config,
-                    ))?;
-                }
-                None => {
-                    nccl_check(ncclCommSplit(
-                        self.inner,
-                        color,
-                        self.rank,
-                        new.as_mut_ptr(),
-                        std::ptr::null_mut(),
-                    ))?;
-                }
-            }
+            nccl_check(ncclCommSplit(
+                self.inner,
+                color,
+                self.rank,
+                new.as_mut_ptr(),
+                std::ptr::null_mut(),
+            ))?;
             new.assume_init()
         };
 

Original file line number	Diff line number	Diff line change
`@@ -11,10 +11,5 @@`
`11`	`11`	`pub(crate) mod ffi {`
`12`	`12`	`unsafe extern "C++" {`
`13`	`13`	`include!("monarch/torch-sys-cuda/src/bridge.h");`
`14`		`-`
`15`		`- // nccl helpers`
`16`		`- #[namespace = ""]`
`17`		`- type ncclConfig_t = nccl_sys::ncclConfig_t;`
`18`		`- fn make_nccl_config() -> ncclConfig_t;`
`19`	`14`	`}`
`20`	`15`	`}`