Performance: cache the backend pages pointer in context

[lttng-modules.git] / lib / ringbuffer / backend_internal.h

diff --git a/lib/ringbuffer/backend_internal.h b/lib/ringbuffer/backend_internal.h
index fc5bec535c591b3d9487e555c0dbbbf2055f5dc9..e03d8c0b1b23a1363fdebbe5ed8589223226983c 100644 (file)
--- a/lib/ringbuffer/backend_internal.h
+++ b/lib/ringbuffer/backend_internal.h
@@ -201,6 +201,37 @@ int subbuffer_id_check_index(const struct lib_ring_buffer_config *config,
                return 0;
 }
 
+static inline
+void lib_ring_buffer_backend_get_pages(const struct lib_ring_buffer_config *config,
+                       struct lib_ring_buffer_ctx *ctx,
+                       struct lib_ring_buffer_backend_pages **backend_pages)
+{
+       struct lib_ring_buffer_backend *bufb = &ctx->buf->backend;
+       struct channel_backend *chanb = &ctx->chan->backend;
+       size_t sbidx, offset = ctx->buf_offset;
+       unsigned long sb_bindex, id;
+       struct lib_ring_buffer_backend_pages *rpages;
+
+       offset &= chanb->buf_size - 1;
+       sbidx = offset >> chanb->subbuf_size_order;
+       id = bufb->buf_wsb[sbidx].id;
+       sb_bindex = subbuffer_id_get_index(config, id);
+       rpages = bufb->array[sb_bindex];
+       CHAN_WARN_ON(ctx->chan,
+                    config->mode == RING_BUFFER_OVERWRITE
+                    && subbuffer_id_is_noref(config, id));
+       *backend_pages = rpages;
+}
+
+/* Get backend pages from cache. */
+static inline
+struct lib_ring_buffer_backend_pages *
+       lib_ring_buffer_get_backend_pages_from_ctx(const struct lib_ring_buffer_config *config,
+               struct lib_ring_buffer_ctx *ctx)
+{
+       return ctx->backend_pages;
+}
+
 /*
  * The ring buffer can count events recorded and overwritten per buffer,
  * but it is disabled by default due to its performance overhead.