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net: QDISC_STATE_RUNNING dont need atomic bit ops

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__QDISC_STATE_RUNNING is always changed while qdisc lock is held.

We can avoid two atomic operations in xmit path, if we move this bit in
a new __state container.

Location of this __state container is carefully chosen so that fast path
only dirties one qdisc cache line.

THROTTLED bit could later be moved into this __state location too, to
avoid dirtying first qdisc cache line.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2010-06-02 03:24:13 -07:00 committed by David S. Miller
parent bc135b23d0
commit 3711210576
1 changed files with 11 additions and 4 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

15
include/net/sch_generic.h
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@ -23,11 +23,17 @@ struct qdisc_rate_table {
};
enum qdisc_state_t {
__QDISC_STATE_RUNNING,
__QDISC_STATE_SCHED,
__QDISC_STATE_DEACTIVATED,
};
/*
* following bits are only changed while qdisc lock is held
*/
enum qdisc___state_t {
__QDISC___STATE_RUNNING,
};
struct qdisc_size_table {
struct list_head list;
struct tc_sizespec szopts;
@ -72,23 +78,24 @@ struct Qdisc {
unsigned long state;
struct sk_buff_head q;
struct gnet_stats_basic_packed bstats;
unsigned long __state;
struct gnet_stats_queue qstats;
struct rcu_head rcu_head;
};
static inline bool qdisc_is_running(struct Qdisc *qdisc)
{
return test_bit(__QDISC_STATE_RUNNING, &qdisc->state);
return test_bit(__QDISC___STATE_RUNNING, &qdisc->__state);
}
static inline bool qdisc_run_begin(struct Qdisc *qdisc)
{
return !test_and_set_bit(__QDISC_STATE_RUNNING, &qdisc->state);
return !__test_and_set_bit(__QDISC___STATE_RUNNING, &qdisc->__state);
}
static inline void qdisc_run_end(struct Qdisc *qdisc)
{
clear_bit(__QDISC_STATE_RUNNING, &qdisc->state);
__clear_bit(__QDISC___STATE_RUNNING, &qdisc->__state);
}
struct Qdisc_class_ops {