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Date: Thu, 12 Oct 2017 14:56:06 -0700
From: Jesus Sanchez-Palencia <jesus.sanchez-palencia@...el.com>
To: Alexander Duyck <alexander.duyck@...il.com>, jiri@...nulli.us,
amritha.nambiar@...el.com, vinicius.gomes@...el.com,
netdev@...r.kernel.org, jhs@...atatu.com, davem@...emloft.net
Subject: Re: [net-next PATCH] mqprio: Reserve last 32 classid values for HW
traffic classes and misc IDs
Hi Alex,
On 10/12/2017 11:38 AM, Alexander Duyck wrote:
> From: Alexander Duyck <alexander.h.duyck@...el.com>
>
> This patch makes a slight tweak to mqprio in order to bring the
> classid values used back in line with what is used for mq. The general idea
> is to reserve values :ffe0 - :ffef to identify hardware traffic classes
> normally reported via dev->num_tc. By doing this we can maintain a
> consistent behavior with mq for classid where :1 - :ffdf will represent a
> physical qdisc mapped onto a Tx queue represented by classid - 1, and the
> traffic classes will be mapped onto a known subset of classid values
> reserved for our virtual qdiscs.
>
> Note I reserved the range from :fff0 - :ffff since this way we might be
> able to reuse these classid values with clsact and ingress which would mean
> that for mq, mqprio, ingress, and clsact we should be able to maintain a
> similar classid layout.
>
> Signed-off-by: Alexander Duyck <alexander.h.duyck@...el.com>
> ---
>
> So I thought I would put this out here as a first step towards trying to
> address some of Jiri's concerns about wanting to have a consistent
> userspace API.
>
> The plan is to follow this up with patches to ingress and clsact to look at
> exposing a set of virtual qdiscs similar to what we already have for the HW
> traffic classes in mqprio, although I won't bother with the ability to dump
> class stats since they don't actually enqueue anything.
>
> include/uapi/linux/pkt_sched.h | 1 +
> net/sched/sch_mqprio.c | 79 +++++++++++++++++++++++-----------------
> 2 files changed, 47 insertions(+), 33 deletions(-)
>
> diff --git a/include/uapi/linux/pkt_sched.h b/include/uapi/linux/pkt_sched.h
> index 099bf5528fed..174f1cf7e7f9 100644
> --- a/include/uapi/linux/pkt_sched.h
> +++ b/include/uapi/linux/pkt_sched.h
> @@ -74,6 +74,7 @@ struct tc_estimator {
> #define TC_H_INGRESS (0xFFFFFFF1U)
> #define TC_H_CLSACT TC_H_INGRESS
>
> +#define TC_H_MIN_PRIORITY 0xFFE0U
> #define TC_H_MIN_INGRESS 0xFFF2U
> #define TC_H_MIN_EGRESS 0xFFF3U
>
> diff --git a/net/sched/sch_mqprio.c b/net/sched/sch_mqprio.c
> index 6bcdfe6e7b63..a61ef119a556 100644
> --- a/net/sched/sch_mqprio.c
> +++ b/net/sched/sch_mqprio.c
> @@ -115,6 +115,10 @@ static int mqprio_init(struct Qdisc *sch, struct nlattr *opt)
> if (!netif_is_multiqueue(dev))
> return -EOPNOTSUPP;
>
> + /* make certain can allocate enough classids to handle queues */
> + if (dev->num_tx_queues >= TC_H_MIN_PRIORITY)
> + return -ENOMEM;
> +
> if (!opt || nla_len(opt) < sizeof(*qopt))
> return -EINVAL;
>
> @@ -193,7 +197,7 @@ static struct netdev_queue *mqprio_queue_get(struct Qdisc *sch,
> unsigned long cl)
> {
> struct net_device *dev = qdisc_dev(sch);
> - unsigned long ntx = cl - 1 - netdev_get_num_tc(dev);
> + unsigned long ntx = cl - 1;
>
> if (ntx >= dev->num_tx_queues)
> return NULL;
> @@ -282,38 +286,35 @@ static unsigned long mqprio_find(struct Qdisc *sch, u32 classid)
> struct net_device *dev = qdisc_dev(sch);
> unsigned int ntx = TC_H_MIN(classid);
>
> - if (ntx > dev->num_tx_queues + netdev_get_num_tc(dev))
> - return 0;
> - return ntx;
> + /* There are essentially two regions here that have valid classid
> + * values. The first region will have a classid value of 1 through
> + * num_tx_queues. All of these are backed by actual Qdiscs.
> + */
> + if (ntx < TC_H_MIN_PRIORITY)
> + return (ntx <= dev->num_tx_queues) ? ntx : 0;
> +
> + /* The second region represents the hardware traffic classes. These
> + * are represented by classid values of TC_H_MIN_PRIORITY through
> + * TC_H_MIN_PRIORITY + netdev_get_num_tc - 1
> + */
> + return ((ntx - TC_H_MIN_PRIORITY) < netdev_get_num_tc(dev)) ? ntx : 0;
> }
>
> static int mqprio_dump_class(struct Qdisc *sch, unsigned long cl,
> struct sk_buff *skb, struct tcmsg *tcm)
> {
> - struct net_device *dev = qdisc_dev(sch);
> + if (cl < TC_H_MIN_PRIORITY) {
> + struct netdev_queue *dev_queue = mqprio_queue_get(sch, cl);
> + struct net_device *dev = qdisc_dev(sch);
> + int tc = netdev_txq_to_tc(dev, cl - 1);
>
> - if (cl <= netdev_get_num_tc(dev)) {
> + tcm->tcm_parent = (tc < 0) ? 0 :
> + TC_H_MAKE(TC_H_MAJ(sch->handle),
> + TC_H_MIN(tc + TC_H_MIN_PRIORITY));
> + tcm->tcm_info = dev_queue->qdisc_sleeping->handle;
> + } else {
> tcm->tcm_parent = TC_H_ROOT;
> tcm->tcm_info = 0;
> - } else {
> - int i;
> - struct netdev_queue *dev_queue;
> -
> - dev_queue = mqprio_queue_get(sch, cl);
> - tcm->tcm_parent = 0;
> - for (i = 0; i < netdev_get_num_tc(dev); i++) {
> - struct netdev_tc_txq tc = dev->tc_to_txq[i];
> - int q_idx = cl - netdev_get_num_tc(dev);
> -
> - if (q_idx > tc.offset &&
> - q_idx <= tc.offset + tc.count) {
> - tcm->tcm_parent =
> - TC_H_MAKE(TC_H_MAJ(sch->handle),
> - TC_H_MIN(i + 1));
> - break;
> - }
> - }
> - tcm->tcm_info = dev_queue->qdisc_sleeping->handle;
> }
> tcm->tcm_handle |= TC_H_MIN(cl);
> return 0;
> @@ -324,15 +325,14 @@ static int mqprio_dump_class_stats(struct Qdisc *sch, unsigned long cl,
> __releases(d->lock)
> __acquires(d->lock)
> {
> - struct net_device *dev = qdisc_dev(sch);
> -
> - if (cl <= netdev_get_num_tc(dev)) {
> + if (cl >= TC_H_MIN_PRIORITY) {
> int i;
> __u32 qlen = 0;
> struct Qdisc *qdisc;
> struct gnet_stats_queue qstats = {0};
> struct gnet_stats_basic_packed bstats = {0};
> - struct netdev_tc_txq tc = dev->tc_to_txq[cl - 1];
> + struct net_device *dev = qdisc_dev(sch);
> + struct netdev_tc_txq tc = dev->tc_to_txq[cl & TC_BITMASK];
>
> /* Drop lock here it will be reclaimed before touching
> * statistics this is required because the d->lock we
> @@ -385,12 +385,25 @@ static void mqprio_walk(struct Qdisc *sch, struct qdisc_walker *arg)
>
> /* Walk hierarchy with a virtual class per tc */
> arg->count = arg->skip;
> - for (ntx = arg->skip;
> - ntx < dev->num_tx_queues + netdev_get_num_tc(dev);
> - ntx++) {
> + for (ntx = arg->skip; ntx < netdev_get_num_tc(dev); ntx++) {
> + if (arg->fn(sch, ntx + TC_H_MIN_PRIORITY, arg) < 0) {
> + arg->stop = 1;
> + return;
> + }
> + arg->count++;
> + }
> +
> + /* Pad the values and skip over unused traffic classes */
> + if (ntx < TC_MAX_QUEUE) {
> + arg->count = TC_MAX_QUEUE;
> + ntx = TC_MAX_QUEUE;
> + }
> +
> + /* Reset offset, sort out remaining per-queue qdiscs */
> + for (ntx -= TC_MAX_QUEUE; ntx < dev->num_tx_queues; ntx++) {
> if (arg->fn(sch, ntx + 1, arg) < 0) {
> arg->stop = 1;
> - break;
> + return;
> }
> arg->count++;
> }
>
Tested-by: Jesus Sanchez-Palencia <jesus.sanchez-palencia@...el.com>
Looks good.
thanks,
Jesus
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