Applied, thanks!
Milos Nikic, le dim. 01 mars 2026 21:37:58 -0800, a ecrit:
> This is an extremely hot path. Add branch prediction hints to the
> error handling and exceptional states to try and squeeze out any
> i-cache benefits that GCC can provide.
>
> Tested by recompiling and booting inside QEMU on x86_64.
>
> * kern/ipc_kobject.c (ipc_kobject_server): Use likely and unlikely macros.
> ---
> kern/ipc_kobject.c | 12 +++++++-----
> 1 file changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/kern/ipc_kobject.c b/kern/ipc_kobject.c
> index 2e727ae..b0554d6 100644
> --- a/kern/ipc_kobject.c
> +++ b/kern/ipc_kobject.c
> @@ -34,6 +34,7 @@
> */
>
> #include <kern/debug.h>
> +#include <kern/macros.h>
> #include <kern/printf.h>
> #include <mach/port.h>
> #include <mach/kern_return.h>
> @@ -87,7 +88,7 @@ ipc_kobject_server(ipc_kmsg_t request)
> ipc_port_t *destp;
>
> reply = ikm_alloc(reply_size);
> - if (reply == IKM_NULL) {
> + if (unlikely(reply == IKM_NULL)) {
> printf("ipc_kobject_server: dropping request\n");
> ipc_kmsg_destroy(request);
> return IKM_NULL;
> @@ -179,8 +180,8 @@ ipc_kobject_server(ipc_kmsg_t request)
> (*routine)(&request->ikm_header, &reply->ikm_header);
> kernel_task->messages_received++;
> } else {
> - if (!ipc_kobject_notify(&request->ikm_header,
> - &reply->ikm_header)) {
> + if (unlikely(!ipc_kobject_notify(&request->ikm_header,
> + &reply->ikm_header))) {
> ((mig_reply_header_t *) &reply->ikm_header)->RetCode
> = MIG_BAD_ID;
> #if MACH_IPC_TEST
> @@ -226,7 +227,7 @@ ipc_kobject_server(ipc_kmsg_t request)
> *destp = IP_NULL;
>
> kr = ((mig_reply_header_t *) &reply->ikm_header)->RetCode;
> - if ((kr == KERN_SUCCESS) || (kr == MIG_NO_REPLY)) {
> + if (likely((kr == KERN_SUCCESS) || (kr == MIG_NO_REPLY))) {
> /*
> * The server function is responsible for the contents
> * of the message. The reply port right is moved
> @@ -258,7 +259,8 @@ ipc_kobject_server(ipc_kmsg_t request)
>
> ikm_free(reply);
> return IKM_NULL;
> - } else if (!IP_VALID((ipc_port_t)reply->ikm_header.msgh_remote_port)) {
> + } else if (unlikely(!IP_VALID(
> + (ipc_port_t)reply->ikm_header.msgh_remote_port))) {
> /*
> * Can't queue the reply message if the destination
> * (the reply port) isn't valid.
> --
> 2.53.0
>
>
--
Samuel
<T> csp.tar.gz: ascii text
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