Add single-stream CUDA benchmark fast path

Signed-off-by: Joe Isaacs <2413449+joseph-isaacs@users.noreply.github.com>

Author: joseph-isaacs

benchmarks/compress-bench/src/main.rs

@@ -25,6 +25,8 @@ use vortex::utils::aliases::hash_map::HashMap;
 use vortex_bench::Engine;
 use vortex_bench::Format;
 use vortex_bench::LogFormat;
+#[cfg(feature = "cuda")]
+use vortex_bench::SESSION;
 use vortex_bench::Target;
 use vortex_bench::compress::CompressMeasurements;
 use vortex_bench::compress::CompressOp;
@@ -52,6 +54,8 @@ use vortex_bench::public_bi::PBIDataset::Food;
 use vortex_bench::public_bi::PBIDataset::HashTags;
 use vortex_bench::setup_logging_and_tracing_with_format;
 use vortex_bench::v3;
+#[cfg(feature = "cuda")]
+use vortex_cuda::CudaSession;
 
 #[derive(Parser, Debug)]
 #[command(version, about, long_about = None)]
@@ -130,6 +134,11 @@ async fn main() -> anyhow::Result<()> {
         direct_io: args.gpu_direct_io,
     });
 
+    #[cfg(feature = "cuda")]
+    if gpu.is_some() {
+        SESSION.register(CudaSession::try_single_stream()?);
+    }
+
     let (formats, ops) = if gpu.is_some() {
         (
             vec![Format::Parquet, Format::OnDiskVortex],

vortex-cuda/src/session.rs

@@ -114,6 +114,30 @@ impl CudaSession {
         }
     }
 
+    /// Creates a single-stream CUDA session using device 0, with event tracking disabled.
+    ///
+    /// Every execution context created from this session shares the same stream. This avoids
+    /// cudarc's per-buffer events, which are only needed to synchronize buffer use across streams.
+    pub fn try_single_stream() -> VortexResult<Self> {
+        // cudarc panics rather than returning an error when the CUDA driver library cannot be
+        // loaded, so catch any unwind here to uphold this constructor's no-panic contract.
+        match catch_unwind(AssertUnwindSafe(|| -> VortexResult<Self> {
+            let context = CudaContext::new(0)
+                .map_err(|err| vortex_err!("failed to initialize CUDA device 0: {err}"))?;
+            // SAFETY: this context is private to a session whose pool contains exactly one stream,
+            // and event tracking is disabled before any device buffers can be allocated.
+            unsafe { context.disable_event_tracking() };
+            let this = Self::with_stream_pool_capacity(context, 1);
+            initialize_cuda(&this);
+            Ok(this)
+        })) {
+            Ok(result) => result,
+            Err(_) => Err(vortex_err!(
+                "failed to initialize CUDA: the driver library is unavailable"
+            )),
+        }
+    }
+
     /// Creates a new CUDA execution context.
     pub fn create_execution_ctx(
         vortex_session: &vortex::session::VortexSession,