Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit ca4ec90b authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

htb: reorder struct htb_class fields for performance 



htb_class structures are big, and source of false sharing on SMP.

By carefully splitting them in two parts, we can improve performance.

I got 9 % performance increase on a 24 threads machine, with 200
concurrent netperf in TCP_RR mode, using a HTB hierarchy of 4 classes.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Cc: Tom Herbert <therbert@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 5f121b9a

net/sched/sch_htb.c

+33 −29
Original line number Diff line number Diff line
@@ -76,23 +76,39 @@ enum htb_cmode { 
	HTB_CAN_SEND		/* class can send */

};



/* interior & leaf nodes; props specific to leaves are marked L: */

/* interior & leaf nodes; props specific to leaves are marked L:

 * To reduce false sharing, place mostly read fields at beginning,

 * and mostly written ones at the end.

 */

struct htb_class {

	struct Qdisc_class_common common;

	/* general class parameters */

	struct gnet_stats_basic_packed bstats;

	struct gnet_stats_queue qstats;

	struct gnet_stats_rate_est64 rate_est;

	struct tc_htb_xstats xstats;	/* our special stats */

	struct psched_ratecfg	rate;

	struct psched_ratecfg	ceil;

	s64			buffer, cbuffer;/* token bucket depth/rate */

	s64			mbuffer;	/* max wait time */

	int			prio;		/* these two are used only by leaves... */

	int			quantum;	/* but stored for parent-to-leaf return */



	struct tcf_proto	*filter_list;	/* class attached filters */

	int			filter_cnt;

	int			refcnt;		/* usage count of this class */



	/* topology */

	int			level;		/* our level (see above) */

	unsigned int		children;

	struct htb_class	*parent;	/* parent class */



	int prio;		/* these two are used only by leaves... */

	int quantum;		/* but stored for parent-to-leaf return */

	struct gnet_stats_rate_est64 rate_est;



	/*

	 * Written often fields

	 */

	struct gnet_stats_basic_packed bstats;

	struct gnet_stats_queue	qstats;

	struct tc_htb_xstats	xstats;	/* our special stats */



	/* token bucket parameters */

	s64			tokens, ctokens;/* current number of tokens */

	s64			t_c;		/* checkpoint time */



	union {

		struct htb_class_leaf {
@@ -111,24 +127,12 @@ struct htb_class { 
			u32 last_ptr_id[TC_HTB_NUMPRIO];

		} inner;

	} un;

	struct rb_node node[TC_HTB_NUMPRIO];	/* node for self or feed tree */

	struct rb_node pq_node;	/* node for event queue */

	s64			pq_key;



	int			prio_activity;	/* for which prios are we active */

	enum htb_cmode		cmode;		/* current mode of the class */



	/* class attached filters */

	struct tcf_proto *filter_list;

	int filter_cnt;



	/* token bucket parameters */

	struct psched_ratecfg rate;

	struct psched_ratecfg ceil;

	s64	buffer, cbuffer;	/* token bucket depth/rate */

	s64	mbuffer;		/* max wait time */

	s64	tokens, ctokens;	/* current number of tokens */

	s64	t_c;			/* checkpoint time */

	struct rb_node		pq_node;	/* node for event queue */

	struct rb_node		node[TC_HTB_NUMPRIO];	/* node for self or feed tree */

};



struct htb_sched {