device is still operational. netdev->queue_lock is still used when the device
comes online or when it's completely shut down (unregister_netdev(), etc.).
-Author: Peter P. Waskiewicz Jr. <peter.p.waskiewicz.jr@intel.com>
+
+Section 2: Qdisc support for multiqueue devices
+
+-----------------------------------------------
+
+Currently two qdiscs support multiqueue devices. The first is the default
+pfifo_fast qdisc. This qdisc supports one qdisc per hardware queue. A new
+round-robin qdisc, sch_multiq also supports multiple hardware queues. The
+qdisc is responsible for classifying the skb's and then directing the skb's to
+bands and queues based on the value in skb->queue_mapping. Use this field in
+the base driver to determine which queue to send the skb to.
+
+sch_multiq has been added for hardware that wishes to avoid unnecessary
+requeuing. It will cycle though the bands and verify that the hardware queue
+associated with the band is not stopped prior to dequeuing a packet.
+
+On qdisc load, the number of bands is based on the number of queues on the
+hardware. Once the association is made, any skb with skb->queue_mapping set,
+will be queued to the band associated with the hardware queue.
+
+
+Section 3: Brief howto using MULTIQ for multiqueue devices
+---------------------------------------------------------------
+
+The userspace command 'tc,' part of the iproute2 package, is used to configure
+qdiscs. To add the MULTIQ qdisc to your network device, assuming the device
+is called eth0, run the following command:
+
+# tc qdisc add dev eth0 root handle 1: multiq
+
+The qdisc will allocate the number of bands to equal the number of queues that
+the device reports, and bring the qdisc online. Assuming eth0 has 4 Tx
+queues, the band mapping would look like:
+
+band 0 => queue 0
+band 1 => queue 1
+band 2 => queue 2
+band 3 => queue 3
+
+Traffic will begin flowing through each queue if your base device has either
+the default simple_tx_hash or a custom netdev->select_queue() defined.
+
+The behavior of tc filters remains the same.
+
+Author: Alexander Duyck <alexander.h.duyck@intel.com>
+Original Author: Peter P. Waskiewicz Jr. <peter.p.waskiewicz.jr@intel.com>
--- /dev/null
+/*
+ * Copyright (c) 2008, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
+ * Place - Suite 330, Boston, MA 02111-1307 USA.
+ *
+ * Author: Alexander Duyck <alexander.h.duyck@intel.com>
+ */
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/errno.h>
+#include <linux/skbuff.h>
+#include <net/netlink.h>
+#include <net/pkt_sched.h>
+
+
+struct multiq_sched_data {
+ u16 bands;
+ u16 max_bands;
+ u16 curband;
+ struct tcf_proto *filter_list;
+ struct Qdisc **queues;
+};
+
+
+static struct Qdisc *
+multiq_classify(struct sk_buff *skb, struct Qdisc *sch, int *qerr)
+{
+ struct multiq_sched_data *q = qdisc_priv(sch);
+ u32 band;
+ struct tcf_result res;
+ int err;
+
+ *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
+ err = tc_classify(skb, q->filter_list, &res);
+#ifdef CONFIG_NET_CLS_ACT
+ switch (err) {
+ case TC_ACT_STOLEN:
+ case TC_ACT_QUEUED:
+ *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
+ case TC_ACT_SHOT:
+ return NULL;
+ }
+#endif
+ band = skb_get_queue_mapping(skb);
+
+ if (band >= q->bands)
+ return q->queues[0];
+
+ return q->queues[band];
+}
+
+static int
+multiq_enqueue(struct sk_buff *skb, struct Qdisc *sch)
+{
+ struct Qdisc *qdisc;
+ int ret;
+
+ qdisc = multiq_classify(skb, sch, &ret);
+#ifdef CONFIG_NET_CLS_ACT
+ if (qdisc == NULL) {
+
+ if (ret & __NET_XMIT_BYPASS)
+ sch->qstats.drops++;
+ kfree_skb(skb);
+ return ret;
+ }
+#endif
+
+ ret = qdisc_enqueue(skb, qdisc);
+ if (ret == NET_XMIT_SUCCESS) {
+ sch->bstats.bytes += qdisc_pkt_len(skb);
+ sch->bstats.packets++;
+ sch->q.qlen++;
+ return NET_XMIT_SUCCESS;
+ }
+ if (net_xmit_drop_count(ret))
+ sch->qstats.drops++;
+ return ret;
+}
+
+
+static int
+multiq_requeue(struct sk_buff *skb, struct Qdisc *sch)
+{
+ struct Qdisc *qdisc;
+ int ret;
+
+ qdisc = multiq_classify(skb, sch, &ret);
+#ifdef CONFIG_NET_CLS_ACT
+ if (qdisc == NULL) {
+ if (ret & __NET_XMIT_BYPASS)
+ sch->qstats.drops++;
+ kfree_skb(skb);
+ return ret;
+ }
+#endif
+
+ ret = qdisc->ops->requeue(skb, qdisc);
+ if (ret == NET_XMIT_SUCCESS) {
+ sch->q.qlen++;
+ sch->qstats.requeues++;
+ return NET_XMIT_SUCCESS;
+ }
+ if (net_xmit_drop_count(ret))
+ sch->qstats.drops++;
+ return ret;
+}
+
+
+static struct sk_buff *multiq_dequeue(struct Qdisc *sch)
+{
+ struct multiq_sched_data *q = qdisc_priv(sch);
+ struct Qdisc *qdisc;
+ struct sk_buff *skb;
+ int band;
+
+ for (band = 0; band < q->bands; band++) {
+ /* cycle through bands to ensure fairness */
+ q->curband++;
+ if (q->curband >= q->bands)
+ q->curband = 0;
+
+ /* Check that target subqueue is available before
+ * pulling an skb to avoid excessive requeues
+ */
+ if (!__netif_subqueue_stopped(qdisc_dev(sch), q->curband)) {
+ qdisc = q->queues[q->curband];
+ skb = qdisc->dequeue(qdisc);
+ if (skb) {
+ sch->q.qlen--;
+ return skb;
+ }
+ }
+ }
+ return NULL;
+
+}
+
+static unsigned int multiq_drop(struct Qdisc *sch)
+{
+ struct multiq_sched_data *q = qdisc_priv(sch);
+ int band;
+ unsigned int len;
+ struct Qdisc *qdisc;
+
+ for (band = q->bands-1; band >= 0; band--) {
+ qdisc = q->queues[band];
+ if (qdisc->ops->drop) {
+ len = qdisc->ops->drop(qdisc);
+ if (len != 0) {
+ sch->q.qlen--;
+ return len;
+ }
+ }
+ }
+ return 0;
+}
+
+
+static void
+multiq_reset(struct Qdisc *sch)
+{
+ u16 band;
+ struct multiq_sched_data *q = qdisc_priv(sch);
+
+ for (band = 0; band < q->bands; band++)
+ qdisc_reset(q->queues[band]);
+ sch->q.qlen = 0;
+ q->curband = 0;
+}
+
+static void
+multiq_destroy(struct Qdisc *sch)
+{
+ int band;
+ struct multiq_sched_data *q = qdisc_priv(sch);
+
+ tcf_destroy_chain(&q->filter_list);
+ for (band = 0; band < q->bands; band++)
+ qdisc_destroy(q->queues[band]);
+
+ kfree(q->queues);
+}
+
+static int multiq_tune(struct Qdisc *sch, struct nlattr *opt)
+{
+ struct multiq_sched_data *q = qdisc_priv(sch);
+ struct tc_multiq_qopt *qopt;
+ int i;
+
+ if (!netif_is_multiqueue(qdisc_dev(sch)))
+ return -EINVAL;
+ if (nla_len(opt) < sizeof(*qopt))
+ return -EINVAL;
+
+ qopt = nla_data(opt);
+
+ qopt->bands = qdisc_dev(sch)->real_num_tx_queues;
+
+ sch_tree_lock(sch);
+ q->bands = qopt->bands;
+ for (i = q->bands; i < q->max_bands; i++) {
+ struct Qdisc *child = xchg(&q->queues[i], &noop_qdisc);
+ if (child != &noop_qdisc) {
+ qdisc_tree_decrease_qlen(child, child->q.qlen);
+ qdisc_destroy(child);
+ }
+ }
+
+ sch_tree_unlock(sch);
+
+ for (i = 0; i < q->bands; i++) {
+ if (q->queues[i] == &noop_qdisc) {
+ struct Qdisc *child;
+ child = qdisc_create_dflt(qdisc_dev(sch),
+ sch->dev_queue,
+ &pfifo_qdisc_ops,
+ TC_H_MAKE(sch->handle,
+ i + 1));
+ if (child) {
+ sch_tree_lock(sch);
+ child = xchg(&q->queues[i], child);
+
+ if (child != &noop_qdisc) {
+ qdisc_tree_decrease_qlen(child,
+ child->q.qlen);
+ qdisc_destroy(child);
+ }
+ sch_tree_unlock(sch);
+ }
+ }
+ }
+ return 0;
+}
+
+static int multiq_init(struct Qdisc *sch, struct nlattr *opt)
+{
+ struct multiq_sched_data *q = qdisc_priv(sch);
+ int i;
+
+ q->queues = NULL;
+
+ if (opt == NULL)
+ return -EINVAL;
+
+ q->max_bands = qdisc_dev(sch)->num_tx_queues;
+
+ q->queues = kcalloc(q->max_bands, sizeof(struct Qdisc *), GFP_KERNEL);
+ if (!q->queues)
+ return -ENOBUFS;
+ for (i = 0; i < q->max_bands; i++)
+ q->queues[i] = &noop_qdisc;
+
+ return multiq_tune(sch, opt);
+}
+
+static int multiq_dump(struct Qdisc *sch, struct sk_buff *skb)
+{
+ struct multiq_sched_data *q = qdisc_priv(sch);
+ unsigned char *b = skb_tail_pointer(skb);
+ struct tc_multiq_qopt opt;
+
+ opt.bands = q->bands;
+ opt.max_bands = q->max_bands;
+
+ NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
+
+ return skb->len;
+
+nla_put_failure:
+ nlmsg_trim(skb, b);
+ return -1;
+}
+
+static int multiq_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
+ struct Qdisc **old)
+{
+ struct multiq_sched_data *q = qdisc_priv(sch);
+ unsigned long band = arg - 1;
+
+ if (band >= q->bands)
+ return -EINVAL;
+
+ if (new == NULL)
+ new = &noop_qdisc;
+
+ sch_tree_lock(sch);
+ *old = q->queues[band];
+ q->queues[band] = new;
+ qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
+ qdisc_reset(*old);
+ sch_tree_unlock(sch);
+
+ return 0;
+}
+
+static struct Qdisc *
+multiq_leaf(struct Qdisc *sch, unsigned long arg)
+{
+ struct multiq_sched_data *q = qdisc_priv(sch);
+ unsigned long band = arg - 1;
+
+ if (band >= q->bands)
+ return NULL;
+
+ return q->queues[band];
+}
+
+static unsigned long multiq_get(struct Qdisc *sch, u32 classid)
+{
+ struct multiq_sched_data *q = qdisc_priv(sch);
+ unsigned long band = TC_H_MIN(classid);
+
+ if (band - 1 >= q->bands)
+ return 0;
+ return band;
+}
+
+static unsigned long multiq_bind(struct Qdisc *sch, unsigned long parent,
+ u32 classid)
+{
+ return multiq_get(sch, classid);
+}
+
+
+static void multiq_put(struct Qdisc *q, unsigned long cl)
+{
+ return;
+}
+
+static int multiq_change(struct Qdisc *sch, u32 handle, u32 parent,
+ struct nlattr **tca, unsigned long *arg)
+{
+ unsigned long cl = *arg;
+ struct multiq_sched_data *q = qdisc_priv(sch);
+
+ if (cl - 1 > q->bands)
+ return -ENOENT;
+ return 0;
+}
+
+static int multiq_delete(struct Qdisc *sch, unsigned long cl)
+{
+ struct multiq_sched_data *q = qdisc_priv(sch);
+ if (cl - 1 > q->bands)
+ return -ENOENT;
+ return 0;
+}
+
+
+static int multiq_dump_class(struct Qdisc *sch, unsigned long cl,
+ struct sk_buff *skb, struct tcmsg *tcm)
+{
+ struct multiq_sched_data *q = qdisc_priv(sch);
+
+ if (cl - 1 > q->bands)
+ return -ENOENT;
+ tcm->tcm_handle |= TC_H_MIN(cl);
+ if (q->queues[cl-1])
+ tcm->tcm_info = q->queues[cl-1]->handle;
+ return 0;
+}
+
+static int multiq_dump_class_stats(struct Qdisc *sch, unsigned long cl,
+ struct gnet_dump *d)
+{
+ struct multiq_sched_data *q = qdisc_priv(sch);
+ struct Qdisc *cl_q;
+
+ cl_q = q->queues[cl - 1];
+ if (gnet_stats_copy_basic(d, &cl_q->bstats) < 0 ||
+ gnet_stats_copy_queue(d, &cl_q->qstats) < 0)
+ return -1;
+
+ return 0;
+}
+
+static void multiq_walk(struct Qdisc *sch, struct qdisc_walker *arg)
+{
+ struct multiq_sched_data *q = qdisc_priv(sch);
+ int band;
+
+ if (arg->stop)
+ return;
+
+ for (band = 0; band < q->bands; band++) {
+ if (arg->count < arg->skip) {
+ arg->count++;
+ continue;
+ }
+ if (arg->fn(sch, band+1, arg) < 0) {
+ arg->stop = 1;
+ break;
+ }
+ arg->count++;
+ }
+}
+
+static struct tcf_proto **multiq_find_tcf(struct Qdisc *sch, unsigned long cl)
+{
+ struct multiq_sched_data *q = qdisc_priv(sch);
+
+ if (cl)
+ return NULL;
+ return &q->filter_list;
+}
+
+static const struct Qdisc_class_ops multiq_class_ops = {
+ .graft = multiq_graft,
+ .leaf = multiq_leaf,
+ .get = multiq_get,
+ .put = multiq_put,
+ .change = multiq_change,
+ .delete = multiq_delete,
+ .walk = multiq_walk,
+ .tcf_chain = multiq_find_tcf,
+ .bind_tcf = multiq_bind,
+ .unbind_tcf = multiq_put,
+ .dump = multiq_dump_class,
+ .dump_stats = multiq_dump_class_stats,
+};
+
+static struct Qdisc_ops multiq_qdisc_ops __read_mostly = {
+ .next = NULL,
+ .cl_ops = &multiq_class_ops,
+ .id = "multiq",
+ .priv_size = sizeof(struct multiq_sched_data),
+ .enqueue = multiq_enqueue,
+ .dequeue = multiq_dequeue,
+ .requeue = multiq_requeue,
+ .drop = multiq_drop,
+ .init = multiq_init,
+ .reset = multiq_reset,
+ .destroy = multiq_destroy,
+ .change = multiq_tune,
+ .dump = multiq_dump,
+ .owner = THIS_MODULE,
+};
+
+static int __init multiq_module_init(void)
+{
+ return register_qdisc(&multiq_qdisc_ops);
+}
+
+static void __exit multiq_module_exit(void)
+{
+ unregister_qdisc(&multiq_qdisc_ops);
+}
+
+module_init(multiq_module_init)
+module_exit(multiq_module_exit)
+
+MODULE_LICENSE("GPL");
projects / GitHub / MotorolaMobilityLLC / kernel-slsi.git / commitdiff