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net_sched: htb: do not setup default rate estimators 

With a thousand htb classes, est_timer() spends ~5 million cpu cycles
and throws out cpu cache, because each htb class has a default
rate estimator (est 4sec 16sec).

Most users do not use default rate estimators, so switch htb
to not setup ones.

Add a module parameter (htb_rate_est) so that users relying
on this default rate estimator can revert the behavior.

echo 1 >/sys/module/sch_htb/parameters/htb_rate_est

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2013-06-06 14:53:16 -07:00 committed by David S. Miller
parent 130d3d68b5
commit 64153ce0a7
1 changed files with 12 additions and 6 deletions
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18
net/sched/sch_htb.c
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@ -65,6 +65,10 @@ static int htb_hysteresis __read_mostly = 0; /* whether to use mode hysteresis f
module_param (htb_hysteresis, int, 0640);
MODULE_PARM_DESC(htb_hysteresis, "Hysteresis mode, less CPU load, less accurate");
static int htb_rate_est = 0; /* htb classes have a default rate estimator */
module_param(htb_rate_est, int, 0640);
MODULE_PARM_DESC(htb_rate_est, "setup a default rate estimator (4sec 16sec) for htb classes");
/* used internaly to keep status of single class */
enum htb_cmode {
HTB_CANT_SEND, /* class can't send and can't borrow */
@ -1366,12 +1370,14 @@ static int htb_change_class(struct Qdisc *sch, u32 classid,
if (!cl)
goto failure;
err = gen_new_estimator(&cl->bstats, &cl->rate_est,
qdisc_root_sleeping_lock(sch),
tca[TCA_RATE] ? : &est.nla);
if (err) {
kfree(cl);
goto failure;
if (htb_rate_est || tca[TCA_RATE]) {
err = gen_new_estimator(&cl->bstats, &cl->rate_est,
qdisc_root_sleeping_lock(sch),
tca[TCA_RATE] ? : &est.nla);
if (err) {
kfree(cl);
goto failure;
}
}
cl->refcnt = 1;