On 11/4/22 15:03, Morten Brørup wrote:
When built with stats enabled (RTE_LIBRTE_MEMPOOL_STATS defined), the
performance of mempools with caches is improved as follows.
When accessing objects in the mempool, either the put_bulk and put_objs or
the get_success_bulk and get_success_objs statistics counters are likely
to be incremented.
By adding an alternative set of these counters to the mempool cache
structure, accessing the dedicated statistics structure is avoided in the
likely cases where these counters are incremented.
The trick here is that the cache line holding the mempool cache structure
is accessed anyway, in order to access the 'len' or 'flushthresh' fields.
Updating some statistics counters in the same cache line has lower
performance cost than accessing the statistics counters in the dedicated
statistics structure, which resides in another cache line.
mempool_perf_autotest with this patch shows the following improvements in
rate_persec.
The cost of enabling mempool stats (without debug) after this patch:
-6.8 % and -6.7 %, respectively without and with cache.
v4:
* Fix checkpatch warnings:
A couple of typos in the patch description.
The macro to add to a mempool cache stat variable should not use
do {} while (0). Personally, I would tend to disagree with this, but
whatever keeps the CI happy.
v3:
* Don't update the description of the RTE_MEMPOOL_STAT_ADD macro.
This change belongs in the first patch of the series.
v2:
* Move the statistics counters into a stats structure.
Signed-off-by: Morten Brørup <m...@smartsharesystems.com>
Reviewed-by: Andrew Rybchenko <andrew.rybche...@oktetlabs.ru>
[snip]
+/**
+ * @internal When stats is enabled, store some statistics.
+ *
+ * @param cache
+ * Pointer to the memory pool cache.
+ * @param name
+ * Name of the statistics field to increment in the memory pool cache.
+ * @param n
+ * Number to add to the statistics.
+ */
+#ifdef RTE_LIBRTE_MEMPOOL_STATS
+#define RTE_MEMPOOL_CACHE_STAT_ADD(cache, name, n) (cache)->stats.name += n
I'd enclose it in parenthesis.
+#else
+#define RTE_MEMPOOL_CACHE_STAT_ADD(cache, name, n) do {} while (0)
+#endif
+
