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dpif-netdev: Add port/queue tiebreaker to rxq_cycle_sort.

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rxq_cycle_sort is used to compare rx queues by their measured number
of cycles. In the event that they are equal, 0 could be returned.
However, it is observed that returning 0 results in a different sort
order on Windows/Linux. This is ok in practice but it causes a unit
test failure for
"1007: PMD - pmd-cpu-mask/distribution of rx queues" when running
on different OS's.

In order to have a consistent sort result across multiple OS's,
introduce a tiebreaker of port/queue.

Fixes: 655856ef39 ("dpif-netdev: Change rxq_scheduling to use rxq processing cycles.")
Reported-by: Alin Gabriel Serdean <aserdean@ovn.org>
Tested-by: Alin Gabriel Serdean <aserdean@ovn.org>
Co-authored-by: Ilya Maximets <i.maximets@samsung.com>
Signed-off-by: Ilya Maximets <i.maximets@samsung.com>
Signed-off-by: Kevin Traynor <ktraynor@redhat.com>
Signed-off-by: Ian Stokes <ian.stokes@intel.com>
This commit is contained in:
Kevin Traynor
2017-11-23 19:41:55 +00:00
committed by Ian Stokes
parent 255b7bda98
commit a130f1a89b
1 changed files with 12 additions and 3 deletions
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15
lib/dpif-netdev.c
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@@ -3463,10 +3463,19 @@ rxq_cycle_sort(const void *a, const void *b)
dp_netdev_rxq_set_cycles(qa, RXQ_CYCLES_PROC_HIST, total_qa);
dp_netdev_rxq_set_cycles(qb, RXQ_CYCLES_PROC_HIST, total_qb);
if (total_qa >= total_qb) {
return -1;
if (total_qa != total_qb) {
return (total_qa < total_qb) ? 1 : -1;
} else {
/* Cycles are the same so tiebreak on port/queue id.
* Tiebreaking (as opposed to return 0) ensures consistent
* sort results across multiple OS's. */
if (qa->port->port_no != qb->port->port_no) {
return (qa->port->port_no > qb->port->port_no) ? 1 : -1;
} else {
return netdev_rxq_get_queue_id(qa->rx)
- netdev_rxq_get_queue_id(qb->rx);
}
}
return 1;
}
/* Assign pmds to queues. If 'pinned' is true, assign pmds to pinned