More tweaks

Signed-off-by: Alan Jowett <[email protected]>

libs/runtime/ebpf_ring_buffer.c

@@ -9,6 +9,7 @@
 typedef struct _ebpf_ring_buffer
 {
     int64_t length;
+    int64_t mask;
     volatile int64_t consumer_offset;
     volatile int64_t producer_offset;
     uint8_t* shared_buffer;
@@ -33,6 +34,7 @@ ebpf_ring_buffer_create(_Outptr_ ebpf_ring_buffer_t** ring, size_t capacity)
     }
 
     local_ring_buffer->length = capacity;
+    local_ring_buffer->mask = capacity - 1;
 
     local_ring_buffer->ring_descriptor = ebpf_allocate_ring_buffer_memory(capacity);
     if (!local_ring_buffer->ring_descriptor) {
@@ -106,7 +108,7 @@ ebpf_ring_buffer_return(_Inout_ ebpf_ring_buffer_t* ring, size_t length)
         }
 
         ebpf_ring_buffer_record_t* record =
-            (ebpf_ring_buffer_record_t*)(ring->shared_buffer + consumer_offset % ring->length);
+            (ebpf_ring_buffer_record_t*)(ring->shared_buffer + (consumer_offset & ring->mask));
 
         long size = ReadAcquire(&record->size);
 
@@ -152,7 +154,7 @@ ebpf_ring_buffer_reserve(
         int64_t producer_offset = ReadAcquire64(&ring->producer_offset);
         // Record points to the next record to allocate.
         ebpf_ring_buffer_record_t* record =
-            (ebpf_ring_buffer_record_t*)(ring->shared_buffer + producer_offset % ring->length);
+            (ebpf_ring_buffer_record_t*)(ring->shared_buffer + (producer_offset & ring->mask));
 
         int64_t remaining_space = ring->length - (producer_offset - ReadAcquire64(&ring->consumer_offset));
         long effective_length = (long)length + 4;
@@ -172,7 +174,7 @@ ebpf_ring_buffer_reserve(
             continue;
         }
 
-        if (InterlockedCompareExchange(&record->size, EBPF_RING_BUFFER_RECORD_FLAG_LOCKED, 0) != 0) {
+        if (InterlockedBitTestAndSetAcquire(&record->size, 31) != 0) {
             continue;
         }
 

libs/runtime/ebpf_ring_buffer.h

@@ -38,6 +38,7 @@ ebpf_ring_buffer_destroy(_Frees_ptr_opt_ ebpf_ring_buffer_t* ring_buffer);
  * @retval EBPF_SUCCESS Successfully wrote record ring buffer.
  * @retval EBPF_OUT_OF_SPACE Unable to output to ring buffer due to inadequate space.
  */
+EBPF_INLINE_HINT
 _Must_inspect_result_ ebpf_result_t
 ebpf_ring_buffer_output(_Inout_ ebpf_ring_buffer_t* ring_buffer, _In_reads_bytes_(length) uint8_t* data, size_t length);