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sched: CHOKe flow scheduler

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CHOKe ("CHOose and Kill" or "CHOose and Keep") is an alternative
packet scheduler based on the Random Exponential Drop (RED) algorithm.

The core idea is:
  For every packet arrival:
  	Calculate Qave
	if (Qave < minth)
	     Queue the new packet
	else
	     Select randomly a packet from the queue
	     if (both packets from same flow)
	     then Drop both the packets
	     else if (Qave > maxth)
	          Drop packet
	     else
	       	  Admit packet with proability p (same as RED)

See also:
  Rong Pan, Balaji Prabhakar, Konstantinos Psounis, "CHOKe: a stateless active
   queue management scheme for approximating fair bandwidth allocation",
  Proceeding of INFOCOM'2000, March 2000.

Help from:
     Eric Dumazet <eric.dumazet@gmail.com>
     Patrick McHardy <kaber@trash.net>

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
stephen hemminger
2011-02-02 15:21:10 +00:00
committed by David S. Miller
parent 119b3d3869
commit 45e144339a
4 changed files with 718 additions and 0 deletions
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29
include/linux/pkt_sched.h
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@ -247,6 +247,35 @@ struct tc_gred_sopt {
__u16 pad1;
};
/* CHOKe section */
enum {
TCA_CHOKE_UNSPEC,
TCA_CHOKE_PARMS,
TCA_CHOKE_STAB,
__TCA_CHOKE_MAX,
};
#define TCA_CHOKE_MAX (__TCA_CHOKE_MAX - 1)
struct tc_choke_qopt {
__u32 limit; /* Hard queue length (packets) */
__u32 qth_min; /* Min average threshold (packets) */
__u32 qth_max; /* Max average threshold (packets) */
unsigned char Wlog; /* log(W) */
unsigned char Plog; /* log(P_max/(qth_max-qth_min)) */
unsigned char Scell_log; /* cell size for idle damping */
unsigned char flags; /* see RED flags */
};
struct tc_choke_xstats {
__u32 early; /* Early drops */
__u32 pdrop; /* Drops due to queue limits */
__u32 other; /* Drops due to drop() calls */
__u32 marked; /* Marked packets */
__u32 matched; /* Drops due to flow match */
};
/* HTB section */
#define TC_HTB_NUMPRIO 8
#define TC_HTB_MAXDEPTH 8