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
This commit is contained in:
Dave Barach
2020-04-09 17:24:07 -04:00
committed by Florin Coras
parent c54162981c
commit c74b43c807
7 changed files with 108 additions and 0 deletions

View File

@ -578,6 +578,14 @@ vlib_buffer_pool_create (vlib_main_t * vm, char *name, u32 data_size,
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_buffers_configure (vlib_main_t * vm, unformat_input_t * input)
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 */
/*