buffers: configurable buffer fault injector
When configured at compile time via the cmake
VPP_BUFFER_FAULT_INJECTOR option, the buffer allocator will appear to
fail a certain fraction of the time.
By default, the allocator succeeds 80% of the time. Detailed command
line configuration options are available, but only when the image has
been compiled with cmake option described above:
vlib { buffer-alloc-success-rate [0.0 ... 1.0]
buffer-alloc-success-seed <nnnn> }
Modify vlib_buffer_pool_create(...) so 0 is always an invalid buffer
index.
Debug images: add checks for bad buffer index enqueues, and also
verify that f->n_vectors doesn't accidentally map one or more
instances of the frame poison pattern 0xfefefefe.
Type: improvement
Signed-off-by: Dave Barach <dave@barachs.net>
Change-Id: Iab939858014463d1e664682805013d334d6fcbe5
diff --git a/src/vlib/buffer.c b/src/vlib/buffer.c
index 43b1dd6..f5b8137 100644
--- a/src/vlib/buffer.c
+++ b/src/vlib/buffer.c
@@ -578,6 +578,14 @@
p = m->base + (j << m->log2_page_size) + i * alloc_size;
p += bm->ext_hdr_size;
+ /*
+ * Waste 1 buffer (maximum) so that 0 is never a valid buffer index.
+ * Allows various places to ASSERT (bi != 0). Much easier
+ * than debugging downstream crashes in successor nodes.
+ */
+ if (p == m->base)
+ continue;
+
vlib_buffer_copy_template ((vlib_buffer_t *) p, &bp->buffer_template);
bi = vlib_get_buffer_index (vm, (vlib_buffer_t *) p);
@@ -923,6 +931,24 @@
VLIB_EARLY_CONFIG_FUNCTION (vlib_buffers_configure, "buffers");
+#if VLIB_BUFFER_ALLOC_FAULT_INJECTOR > 0
+u32
+vlib_buffer_alloc_may_fail (vlib_main_t * vm, u32 n_buffers)
+{
+ f64 r;
+
+ r = random_f64 (&vm->buffer_alloc_success_seed);
+
+ /* Fail this request? */
+ if (r > vm->buffer_alloc_success_rate)
+ n_buffers--;
+ /* 5% chance of returning nothing at all */
+ if (r > vm->buffer_alloc_success_rate && r > 0.95)
+ n_buffers = 0;
+
+ return n_buffers;
+}
+#endif
/** @endcond */
/*