[ovs-dev] [v1 v1 3/6] dpif-netdev: Add study function to select the best mfex function.
Kumar Amber
kumar.amber at intel.com
Wed Apr 28 07:55:51 UTC 2021
The study function runs all the available implementations
of miniflow_extract and makes a choice whose hitmask has
maximum hits and sets the mfex to that function.
Study can be run at runtime using the following command:
$ ovs-appctl dpif-netdev/miniflow-parser-set study
Signed-off-by: Kumar Amber <kumar.amber at intel.com>
Co-authored-by: Harry van Haaren <harry.van.haaren at intel.com>
Signed-off-by: Harry van Haaren <harry.van.haaren at intel.com>
---
lib/automake.mk | 1 +
lib/dpif-netdev-extract-study.c | 120 ++++++++++++++++++++++++++++++
lib/dpif-netdev-private-extract.c | 5 ++
lib/dpif-netdev-private-extract.h | 14 +++-
4 files changed, 139 insertions(+), 1 deletion(-)
create mode 100644 lib/dpif-netdev-extract-study.c
diff --git a/lib/automake.mk b/lib/automake.mk
index f3fba6572..783730fc7 100644
--- a/lib/automake.mk
+++ b/lib/automake.mk
@@ -113,6 +113,7 @@ lib_libopenvswitch_la_SOURCES = \
lib/dpif-netdev-lookup-generic.c \
lib/dpif-netdev.c \
lib/dpif-netdev.h \
+ lib/dpif-netdev-extract-study.c \
lib/dpif-netdev-private-dfc.h \
lib/dpif-netdev-private-dpcls.h \
lib/dpif-netdev-private-dpif.c \
diff --git a/lib/dpif-netdev-extract-study.c b/lib/dpif-netdev-extract-study.c
new file mode 100644
index 000000000..8c0910393
--- /dev/null
+++ b/lib/dpif-netdev-extract-study.c
@@ -0,0 +1,120 @@
+/*
+ * Copyright (c) 2021 Intel.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <config.h>
+#include <errno.h>
+#include <stdint.h>
+#include <string.h>
+
+#include "dpif-netdev-private-extract.h"
+#include "dpif-netdev-private-thread.h"
+#include "openvswitch/vlog.h"
+#include "ovs-thread.h"
+
+VLOG_DEFINE_THIS_MODULE(dpif_mfex_extract_study);
+
+/* Max size of packets to be compared. */
+#define MFEX_MAX_COUNT (128)
+
+/* This value is the threshold for the amount of packets that
+ * must hit on the optimized miniflow extract before it will be
+ * accepted and used in the datapath after the study phase. */
+#define MFEX_MIN_HIT_COUNT_FOR_USE (MFEX_MAX_COUNT / 2)
+
+/* Struct to hold miniflow study stats. */
+struct study_stats {
+ uint32_t pkt_count;
+ uint32_t impl_hitcount[MFEX_IMPLS_MAX_SIZE];
+};
+
+/* Define per thread data to hold the study stats. */
+DEFINE_PER_THREAD_MALLOCED_DATA(struct study_stats *, study_stats);
+
+/* Allocate per thread PMD pointer space for study_stats. */
+static inline struct study_stats *
+get_study_stats(void)
+{
+ struct study_stats *stats = study_stats_get();
+ if (OVS_UNLIKELY(!stats)) {
+ stats = xzalloc(sizeof *stats);
+ study_stats_set_unsafe(stats);
+ }
+ return stats;
+}
+
+uint32_t
+mfex_study_traffic(struct dp_packet_batch *packets,
+ struct netdev_flow_key *keys,
+ uint32_t keys_size, odp_port_t in_port,
+ void *pmd_handle)
+{
+ uint32_t hitmask = 0;
+ uint32_t mask = 0;
+ struct dp_packet *packet;
+ struct dp_netdev_pmd_thread *pmd = pmd_handle;
+ struct dpif_miniflow_extract_impl *miniflow_funcs;
+ uint32_t impl_count = dpif_miniflow_extract_info_get(&miniflow_funcs);
+ struct study_stats *stats = get_study_stats();
+
+ /* Run traffic optimized miniflow_extract to collect the hitmask
+ * to be compared after certain packets have been hit to choose
+ * the best miniflow_extract version for that traffic. */
+ for (int i = MFEX_IMPL_START_IDX; i < impl_count; i++) {
+ if (miniflow_funcs[i].available) {
+ hitmask = miniflow_funcs[i].extract_func(packets, keys, keys_size,
+ in_port, pmd_handle);
+ stats->impl_hitcount[i] += count_1bits(hitmask);
+
+ /* If traffic is not classified than we dont overwrite the keys
+ * array in minfiflow implementations so its safe to create a
+ * mask for all those packets whose miniflow have been created. */
+ mask |= hitmask;
+ }
+ }
+ stats->pkt_count += dp_packet_batch_size(packets);
+
+ /* Choose the best implementation after a minimum packets have been
+ * processed. */
+ if (stats->pkt_count >= MFEX_MAX_COUNT) {
+ uint32_t best_func_index = MFEX_IMPL_START_IDX;
+ uint32_t max_hits = 0;
+ for (int i = MFEX_IMPL_START_IDX; i < impl_count; i++) {
+ if (stats->impl_hitcount[i] > max_hits) {
+ max_hits = stats->impl_hitcount[i];
+ best_func_index = i;
+ }
+ }
+
+ if (max_hits >= MFEX_MIN_HIT_COUNT_FOR_USE) {
+ /* Set the implementation to index with max_hits. */
+ pmd->miniflow_extract_opt =
+ miniflow_funcs[best_func_index].extract_func;
+ VLOG_INFO("MFEX study chose impl %s: (hits %d/%d pkts)\n",
+ miniflow_funcs[best_func_index].name, max_hits,
+ stats->pkt_count);
+ } else {
+ /* Set the implementation to null for default miniflow. */
+ pmd->miniflow_extract_opt = NULL;
+ VLOG_INFO("Not enough packets matched (%d/%d), disabling"
+ " optimized MFEX.\n", max_hits, stats->pkt_count);
+ }
+ /* Reset stats so that study function can be called again
+ * for next traffic type and optimal function ptr can be
+ * choosen. */
+ memset(stats, 0, sizeof(struct study_stats));
+ }
+ return mask;
+}
diff --git a/lib/dpif-netdev-private-extract.c b/lib/dpif-netdev-private-extract.c
index 9a53d4985..76c24c2f8 100644
--- a/lib/dpif-netdev-private-extract.c
+++ b/lib/dpif-netdev-private-extract.c
@@ -42,6 +42,11 @@ static struct dpif_miniflow_extract_impl mfex_impls[] = {
.extract_func = NULL,
.name = "disable",
},
+ {
+ .probe = NULL,
+ .extract_func = mfex_study_traffic,
+ .name = "study",
+ },
};
BUILD_ASSERT_DECL(MFEX_IMPLS_MAX_SIZE > ARRAY_SIZE(mfex_impls));
diff --git a/lib/dpif-netdev-private-extract.h b/lib/dpif-netdev-private-extract.h
index 455a7b590..3ada413bb 100644
--- a/lib/dpif-netdev-private-extract.h
+++ b/lib/dpif-netdev-private-extract.h
@@ -27,7 +27,7 @@
/* Skip the autovalidator study and null when iterating all available
* miniflow implementations.
*/
-#define MFEX_IMPL_START_IDX (1)
+#define MFEX_IMPL_START_IDX (3)
/* Forward declarations. */
struct dp_packet;
@@ -106,4 +106,16 @@ dpif_miniflow_extract_autovalidator(struct dp_packet_batch *batch,
uint32_t keys_size, odp_port_t in_port,
void *pmd_handle);
+/* Retrieve the number of packets by studying packets using different miniflow
+ * implementations to choose the best implementation using the maximum hitmask
+ * count.
+ * On error, returns a zero for no packets.
+ * On success, returns mask of the packets hit.
+ */
+uint32_t
+mfex_study_traffic(struct dp_packet_batch *packets,
+ struct netdev_flow_key *keys,
+ uint32_t keys_size, odp_port_t in_port,
+ void *pmd_handle);
+
#endif /* DPIF_NETDEV_AVX512_EXTRACT */
--
2.25.1
More information about the dev
mailing list