[ovs-dev,v3,5/6] dpif-netdev: Change pmd selection order.

Message ID 1501603092-6287-6-git-send-email-ktraynor@redhat.com
State Superseded
Delegated to: Darrell Ball
Headers show

Commit Message

Kevin Traynor Aug. 1, 2017, 3:58 p.m.
Up to his point rxqs are sorted by processing cycles they
consumed and assigned to pmds in a round robin manner.

Ian pointed out that on wrap around the most loaded pmd will be
the next one to be assigned an additional rxq and that it would be
better to reverse the pmd order when wraparound occurs.

In other words, change from assigning by rr to assigning in a forward
and reverse cycle through pmds.

Also, now that the algothim has finalised, document an example.

Suggested-by: Ian Stokes <ian.stokes@intel.com>
Signed-off-by: Kevin Traynor <ktraynor@redhat.com>
---
 Documentation/howto/dpdk.rst | 16 ++++++++++++++++
 lib/dpif-netdev.c            | 21 ++++++++++++++++++++-
 tests/pmd.at                 |  2 +-
 3 files changed, 37 insertions(+), 2 deletions(-)

Patch

diff --git a/Documentation/howto/dpdk.rst b/Documentation/howto/dpdk.rst
index a969285..c7bac4e 100644
--- a/Documentation/howto/dpdk.rst
+++ b/Documentation/howto/dpdk.rst
@@ -124,4 +124,20 @@  will be used where known to assign rxqs with the highest consumption of
 processing cycles to different pmds.
 
+For example, in the case where here there are 5 rxqs and 3 cores (e.g. 3,7,8)
+available, and the measured usage of core cycles per rxq over the last
+interval is seen to be:
+
+- Queue #0: 30%
+- Queue #1: 80%
+- Queue #3: 60%
+- Queue #4: 70%
+- Queue #5: 10%
+
+The rxqs will be assigned to cores 3,7,8 in the following order:
+
+Core 3: Q1 (80%) |
+Core 7: Q4 (70%) | Q5 (10%)
+core 8: Q0 (60%) | Q0 (30%)
+
 Rxq to pmds assignment takes place whenever there are configuration changes.
 
diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
index a05e586..3f174c8 100644
--- a/lib/dpif-netdev.c
+++ b/lib/dpif-netdev.c
@@ -3236,4 +3236,5 @@  struct rr_numa {
 
     int cur_index;
+    bool idx_inc;
 };
 
@@ -3274,4 +3275,7 @@  rr_numa_list_populate(struct dp_netdev *dp, struct rr_numa_list *rr)
         numa->pmds = xrealloc(numa->pmds, numa->n_pmds * sizeof *numa->pmds);
         numa->pmds[numa->n_pmds - 1] = pmd;
+        /* At least one pmd so initialise curr_idx and idx_inc. */
+        numa->cur_index = 0;
+        numa->idx_inc = true;
     }
 }
@@ -3280,5 +3284,20 @@  static struct dp_netdev_pmd_thread *
 rr_numa_get_pmd(struct rr_numa *numa)
 {
-    return numa->pmds[numa->cur_index++ % numa->n_pmds];
+    int numa_idx = numa->cur_index;
+
+    if (numa->idx_inc == true) {
+        if (numa->cur_index == numa->n_pmds-1) {
+            numa->idx_inc = false;
+        } else {
+            numa->cur_index++;
+        }
+    } else {
+        if (numa->cur_index == 0) {
+            numa->idx_inc = true;
+        } else {
+            numa->cur_index--;
+        }
+    }
+    return numa->pmds[numa_idx];
 }
 
diff --git a/tests/pmd.at b/tests/pmd.at
index f95a016..73a8be1 100644
--- a/tests/pmd.at
+++ b/tests/pmd.at
@@ -54,5 +54,5 @@  m4_define([CHECK_PMD_THREADS_CREATED], [
 
 m4_define([SED_NUMA_CORE_PATTERN], ["s/\(numa_id \)[[0-9]]*\( core_id \)[[0-9]]*:/\1<cleared>\2<cleared>:/"])
-m4_define([SED_NUMA_CORE_QUEUE_PATTERN], ["s/\(numa_id \)[[0-9]]*\( core_id \)[[0-9]]*:/\1<cleared>\2<cleared>:/;s/\(queue-id: \)0 2 4 6/\1<cleared>/;s/\(queue-id: \)1 3 5 7/\1<cleared>/"])
+m4_define([SED_NUMA_CORE_QUEUE_PATTERN], ["s/\(numa_id \)[[0-9]]*\( core_id \)[[0-9]]*:/\1<cleared>\2<cleared>:/;s/\(queue-id: \)1 2 5 6/\1<cleared>/;s/\(queue-id: \)0 3 4 7/\1<cleared>/"])
 m4_define([DUMMY_NUMA], [--dummy-numa="0,0,0,0"])