[dpdk-dev] distributor: add comments to make code more readable
Commit Message
From: "Bruce Richardson" <bruce.richardson@intel.com>
Add in some additional comments around more complex areas of the code
so as to make the code easier to read and understand.
Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
---
lib/librte_distributor/rte_distributor.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
Comments
2014-11-06 13:55, Bruce Richardson:
> From: "Bruce Richardson" <bruce.richardson@intel.com>
>
> Add in some additional comments around more complex areas of the code
> so as to make the code easier to read and understand.
>
> Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Applied
Qinglai, if you change the design, you'll now have some comments to update ;)
Thanks
Hi Thomas,
Thanks for the reminder. I didn't notice the change in comments yet.
thx &
rgds,
-qinglai
On Fri, Nov 7, 2014 at 4:08 PM, Thomas Monjalon <thomas.monjalon@6wind.com>
wrote:
> 2014-11-06 13:55, Bruce Richardson:
> > From: "Bruce Richardson" <bruce.richardson@intel.com>
> >
> > Add in some additional comments around more complex areas of the code
> > so as to make the code easier to read and understand.
> >
> > Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
>
> Applied
>
> Qinglai, if you change the design, you'll now have some comments to update
> ;)
>
> Thanks
> --
> Thomas
>
@@ -92,6 +92,7 @@ struct rte_distributor {
unsigned num_workers; /**< Number of workers polling */
uint32_t in_flight_tags[RTE_MAX_LCORE];
+ /**< Tracks the tag being processed per core, 0 == no pkt */
struct rte_distributor_backlog backlog[RTE_MAX_LCORE];
union rte_distributor_buffer bufs[RTE_MAX_LCORE];
@@ -282,10 +283,22 @@ rte_distributor_process(struct rte_distributor *d,
next_mb = mbufs[next_idx++];
next_value = (((int64_t)(uintptr_t)next_mb)
<< RTE_DISTRIB_FLAG_BITS);
+ /*
+ * Set the low bit on the tag, so we can guarantee that
+ * we never store a tag value of zero. That means we can
+ * use the zero-value to indicate that no packet is
+ * being processed by a worker.
+ */
new_tag = (next_mb->hash.rss | 1);
uint32_t match = 0;
unsigned i;
+ /*
+ * to scan for a match use "xor" and "not" to get a 0/1
+ * value, then use shifting to merge to single "match"
+ * variable, where a one-bit indicates a match for the
+ * worker given by the bit-position
+ */
for (i = 0; i < d->num_workers; i++)
match |= (!(d->in_flight_tags[i] ^ new_tag)
<< i);