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htb: reorder struct htb_class fields for performance

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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: Eric Dumazet <edumazet@google.com>
Cc: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2013-06-13 07:58:30 -07:00 committed by David S. Miller
parent 5f121b9a83
commit ca4ec90b31
1 changed files with 33 additions and 29 deletions
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62
net/sched/sch_htb.c
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@ -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 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 */
int level; /* our level (see above) */
unsigned int children;
struct htb_class *parent; /* parent class */
struct gnet_stats_rate_est64 rate_est;
struct tc_htb_xstats xstats; /* our special stats */
int refcnt; /* usage count of this class */
/* topology */
int level; /* our level (see above) */
unsigned int children;
struct htb_class *parent; /* parent class */
/*
* Written often fields
*/
struct gnet_stats_basic_packed bstats;
struct gnet_stats_queue qstats;
struct tc_htb_xstats xstats; /* our special stats */
int prio; /* these two are used only by leaves... */
int quantum; /* but stored for parent-to-leaf return */
/* 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;
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 */
int prio_activity; /* for which prios are we active */
enum htb_cmode cmode; /* current mode of the class */
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 {