Switch the default to using the faster kernels. (#1978)

* Switch the default to using the faster kernels.

* Add the force-dmmv flag.

candle-core/src/quantized/cuda.rs

@@ -10,7 +10,7 @@ pub struct QCudaStorage {
     device: CudaDevice,
 }
 
-static FORCE_DMMV: std::sync::atomic::AtomicBool = std::sync::atomic::AtomicBool::new(true);
+static FORCE_DMMV: std::sync::atomic::AtomicBool = std::sync::atomic::AtomicBool::new(false);
 
 pub fn set_force_dmmv(f: bool) {
     FORCE_DMMV.store(f, std::sync::atomic::Ordering::Relaxed)

candle-examples/examples/mistral/main.rs

@@ -196,6 +196,10 @@ struct Args {
     /// The context size to consider for the repeat penalty.
     #[arg(long, default_value_t = 64)]
     repeat_last_n: usize,
+
+    /// Use the slower dmmv cuda kernel.
+    #[arg(long)]
+    force_dmmv: bool,
 }
 
 fn main() -> Result<()> {
@@ -203,6 +207,9 @@ fn main() -> Result<()> {
     use tracing_subscriber::prelude::*;
 
     let args = Args::parse();
+    #[cfg(feature = "cuda")]
+    candle::quantized::cuda::set_force_dmmv(args.force_dmmv);
+
     let _guard = if args.tracing {
         let (chrome_layer, guard) = ChromeLayerBuilder::new().build();
         tracing_subscriber::registry().with(chrome_layer).init();

candle-examples/examples/quantized/main.rs

@@ -236,9 +236,9 @@ struct Args {
     #[arg(long)]
     gqa: Option<usize>,
 
-    /// Use the (experimental) fast cuda kernels.
+    /// Use the slower dmmv cuda kernel.
     #[arg(long)]
-    fast_cuda: bool,
+    force_dmmv: bool,
 }
 
 impl Args {
@@ -347,7 +347,7 @@ fn main() -> anyhow::Result<()> {
     let args = Args::parse();
 
     #[cfg(feature = "cuda")]
-    candle::quantized::cuda::set_force_dmmv(!args.fast_cuda);
+    candle::quantized::cuda::set_force_dmmv(args.force_dmmv);
 
     let temperature = if args.temperature == 0. {
         None