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Commit 37112105 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

net: QDISC_STATE_RUNNING dont need atomic bit ops 



__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: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent bc135b23

include/net/sch_generic.h

+11 −4
Original line number Original line Diff line number Diff line
@@ -23,11 +23,17 @@ struct qdisc_rate_table { 
};

};





enum qdisc_state_t {

enum qdisc_state_t {

	__QDISC_STATE_RUNNING,

	__QDISC_STATE_SCHED,

	__QDISC_STATE_SCHED,

	__QDISC_STATE_DEACTIVATED,

	__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 qdisc_size_table {

	struct list_head	list;

	struct list_head	list;

	struct tc_sizespec	szopts;

	struct tc_sizespec	szopts;
@@ -72,23 +78,24 @@ struct Qdisc { 
	unsigned long		state;

	unsigned long		state;

	struct sk_buff_head	q;

	struct sk_buff_head	q;

	struct gnet_stats_basic_packed bstats;

	struct gnet_stats_basic_packed bstats;

	unsigned long		__state;

	struct gnet_stats_queue	qstats;

	struct gnet_stats_queue	qstats;

	struct rcu_head     rcu_head;

	struct rcu_head     rcu_head;

};

};





static inline bool qdisc_is_running(struct Qdisc *qdisc)

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)

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)

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 {

struct Qdisc_class_ops {