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https://github.com/torvalds/linux
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d0a81f67cd
The default TX queue length of Ethernet devices have been a magic constant of 1000, ever since the initial git import. Looking back in historical trees[1][2] the value used to be 100, with the same comment "Ethernet wants good queues". The commit[3] that changed this from 100 to 1000 didn't describe why, but from conversations with Robert Olsson it seems that it was changed when Ethernet devices went from 100Mbit/s to 1Gbit/s, because the link speed increased x10 the queue size were also adjusted. This value later caused much heartache for the bufferbloat community. This patch merely moves the value into a defined constant. [1] https://git.kernel.org/cgit/linux/kernel/git/davem/netdev-vger-cvs.git/ [2] https://git.kernel.org/cgit/linux/kernel/git/tglx/history.git/ [3] https://git.kernel.org/tglx/history/c/98921832c232 Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
138 lines
3.8 KiB
C
138 lines
3.8 KiB
C
#ifndef __NET_PKT_SCHED_H
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#define __NET_PKT_SCHED_H
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#include <linux/jiffies.h>
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#include <linux/ktime.h>
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#include <linux/if_vlan.h>
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#include <net/sch_generic.h>
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#define DEFAULT_TX_QUEUE_LEN 1000
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struct qdisc_walker {
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int stop;
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int skip;
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int count;
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int (*fn)(struct Qdisc *, unsigned long cl, struct qdisc_walker *);
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};
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#define QDISC_ALIGNTO 64
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#define QDISC_ALIGN(len) (((len) + QDISC_ALIGNTO-1) & ~(QDISC_ALIGNTO-1))
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static inline void *qdisc_priv(struct Qdisc *q)
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{
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return (char *) q + QDISC_ALIGN(sizeof(struct Qdisc));
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}
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/*
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Timer resolution MUST BE < 10% of min_schedulable_packet_size/bandwidth
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Normal IP packet size ~ 512byte, hence:
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0.5Kbyte/1Mbyte/sec = 0.5msec, so that we need 50usec timer for
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10Mbit ethernet.
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10msec resolution -> <50Kbit/sec.
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The result: [34]86 is not good choice for QoS router :-(
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The things are not so bad, because we may use artificial
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clock evaluated by integration of network data flow
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in the most critical places.
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*/
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typedef u64 psched_time_t;
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typedef long psched_tdiff_t;
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/* Avoid doing 64 bit divide */
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#define PSCHED_SHIFT 6
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#define PSCHED_TICKS2NS(x) ((s64)(x) << PSCHED_SHIFT)
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#define PSCHED_NS2TICKS(x) ((x) >> PSCHED_SHIFT)
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#define PSCHED_TICKS_PER_SEC PSCHED_NS2TICKS(NSEC_PER_SEC)
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#define PSCHED_PASTPERFECT 0
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static inline psched_time_t psched_get_time(void)
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{
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return PSCHED_NS2TICKS(ktime_get_ns());
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}
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static inline psched_tdiff_t
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psched_tdiff_bounded(psched_time_t tv1, psched_time_t tv2, psched_time_t bound)
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{
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return min(tv1 - tv2, bound);
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}
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struct qdisc_watchdog {
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u64 last_expires;
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struct hrtimer timer;
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struct Qdisc *qdisc;
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};
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void qdisc_watchdog_init(struct qdisc_watchdog *wd, struct Qdisc *qdisc);
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void qdisc_watchdog_schedule_ns(struct qdisc_watchdog *wd, u64 expires);
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static inline void qdisc_watchdog_schedule(struct qdisc_watchdog *wd,
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psched_time_t expires)
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{
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qdisc_watchdog_schedule_ns(wd, PSCHED_TICKS2NS(expires));
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}
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void qdisc_watchdog_cancel(struct qdisc_watchdog *wd);
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extern struct Qdisc_ops pfifo_qdisc_ops;
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extern struct Qdisc_ops bfifo_qdisc_ops;
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extern struct Qdisc_ops pfifo_head_drop_qdisc_ops;
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int fifo_set_limit(struct Qdisc *q, unsigned int limit);
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struct Qdisc *fifo_create_dflt(struct Qdisc *sch, struct Qdisc_ops *ops,
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unsigned int limit);
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int register_qdisc(struct Qdisc_ops *qops);
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int unregister_qdisc(struct Qdisc_ops *qops);
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void qdisc_get_default(char *id, size_t len);
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int qdisc_set_default(const char *id);
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void qdisc_hash_add(struct Qdisc *q);
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void qdisc_hash_del(struct Qdisc *q);
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struct Qdisc *qdisc_lookup(struct net_device *dev, u32 handle);
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struct Qdisc *qdisc_lookup_class(struct net_device *dev, u32 handle);
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struct qdisc_rate_table *qdisc_get_rtab(struct tc_ratespec *r,
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struct nlattr *tab);
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void qdisc_put_rtab(struct qdisc_rate_table *tab);
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void qdisc_put_stab(struct qdisc_size_table *tab);
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void qdisc_warn_nonwc(const char *txt, struct Qdisc *qdisc);
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int sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q,
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struct net_device *dev, struct netdev_queue *txq,
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spinlock_t *root_lock, bool validate);
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void __qdisc_run(struct Qdisc *q);
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static inline void qdisc_run(struct Qdisc *q)
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{
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if (qdisc_run_begin(q))
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__qdisc_run(q);
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}
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int tc_classify(struct sk_buff *skb, const struct tcf_proto *tp,
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struct tcf_result *res, bool compat_mode);
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static inline __be16 tc_skb_protocol(const struct sk_buff *skb)
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{
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/* We need to take extra care in case the skb came via
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* vlan accelerated path. In that case, use skb->vlan_proto
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* as the original vlan header was already stripped.
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*/
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if (skb_vlan_tag_present(skb))
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return skb->vlan_proto;
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return skb->protocol;
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}
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/* Calculate maximal size of packet seen by hard_start_xmit
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routine of this device.
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*/
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static inline unsigned int psched_mtu(const struct net_device *dev)
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{
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return dev->mtu + dev->hard_header_len;
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}
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#endif
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