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[TCP]: cleanup of htcp (resend)
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Minor non-invasive cleanups:
 * white space around operators and line wrapping
 * use const
 * use __read_mostly

Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Stephen Hemminger authored and David S. Miller committed Feb 12, 2007
1 parent 59758f4 commit 9121c77
Showing 1 changed file with 37 additions and 28 deletions.
65 changes: 37 additions & 28 deletions net/ipv4/tcp_htcp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -10,22 +10,23 @@
#include <linux/module.h>
#include <net/tcp.h>

#define ALPHA_BASE (1<<7) /* 1.0 with shift << 7 */
#define BETA_MIN (1<<6) /* 0.5 with shift << 7 */
#define ALPHA_BASE (1<<7) /* 1.0 with shift << 7 */
#define BETA_MIN (1<<6) /* 0.5 with shift << 7 */
#define BETA_MAX 102 /* 0.8 with shift << 7 */

static int use_rtt_scaling = 1;
static int use_rtt_scaling __read_mostly = 1;
module_param(use_rtt_scaling, int, 0644);
MODULE_PARM_DESC(use_rtt_scaling, "turn on/off RTT scaling");

static int use_bandwidth_switch = 1;
static int use_bandwidth_switch __read_mostly = 1;
module_param(use_bandwidth_switch, int, 0644);
MODULE_PARM_DESC(use_bandwidth_switch, "turn on/off bandwidth switcher");

struct htcp {
u32 alpha; /* Fixed point arith, << 7 */
u8 beta; /* Fixed point arith, << 7 */
u8 modeswitch; /* Delay modeswitch until we had at least one congestion event */
u8 modeswitch; /* Delay modeswitch
until we had at least one congestion event */
u16 pkts_acked;
u32 packetcount;
u32 minRTT;
Expand All @@ -44,14 +45,14 @@ struct htcp {
u32 lasttime;
};

static inline u32 htcp_cong_time(struct htcp *ca)
static inline u32 htcp_cong_time(const struct htcp *ca)
{
return jiffies - ca->last_cong;
}

static inline u32 htcp_ccount(struct htcp *ca)
static inline u32 htcp_ccount(const struct htcp *ca)
{
return htcp_cong_time(ca)/ca->minRTT;
return htcp_cong_time(ca) / ca->minRTT;
}

static inline void htcp_reset(struct htcp *ca)
Expand All @@ -67,28 +68,32 @@ static u32 htcp_cwnd_undo(struct sock *sk)
{
const struct tcp_sock *tp = tcp_sk(sk);
struct htcp *ca = inet_csk_ca(sk);

ca->last_cong = ca->undo_last_cong;
ca->maxRTT = ca->undo_maxRTT;
ca->old_maxB = ca->undo_old_maxB;
return max(tp->snd_cwnd, (tp->snd_ssthresh<<7)/ca->beta);

return max(tp->snd_cwnd, (tp->snd_ssthresh << 7) / ca->beta);
}

static inline void measure_rtt(struct sock *sk)
{
const struct inet_connection_sock *icsk = inet_csk(sk);
const struct tcp_sock *tp = tcp_sk(sk);
struct htcp *ca = inet_csk_ca(sk);
u32 srtt = tp->srtt>>3;
u32 srtt = tp->srtt >> 3;

/* keep track of minimum RTT seen so far, minRTT is zero at first */
if (ca->minRTT > srtt || !ca->minRTT)
ca->minRTT = srtt;

/* max RTT */
if (icsk->icsk_ca_state == TCP_CA_Open && tp->snd_ssthresh < 0xFFFF && htcp_ccount(ca) > 3) {
if (icsk->icsk_ca_state == TCP_CA_Open
&& tp->snd_ssthresh < 0xFFFF && htcp_ccount(ca) > 3) {
if (ca->maxRTT < ca->minRTT)
ca->maxRTT = ca->minRTT;
if (ca->maxRTT < srtt && srtt <= ca->maxRTT+msecs_to_jiffies(20))
if (ca->maxRTT < srtt
&& srtt <= ca->maxRTT + msecs_to_jiffies(20))
ca->maxRTT = srtt;
}
}
Expand Down Expand Up @@ -116,15 +121,16 @@ static void measure_achieved_throughput(struct sock *sk, u32 pkts_acked)

ca->packetcount += pkts_acked;

if (ca->packetcount >= tp->snd_cwnd - (ca->alpha>>7? : 1)
&& now - ca->lasttime >= ca->minRTT
&& ca->minRTT > 0) {
__u32 cur_Bi = ca->packetcount*HZ/(now - ca->lasttime);
if (ca->packetcount >= tp->snd_cwnd - (ca->alpha >> 7 ? : 1)
&& now - ca->lasttime >= ca->minRTT
&& ca->minRTT > 0) {
__u32 cur_Bi = ca->packetcount * HZ / (now - ca->lasttime);

if (htcp_ccount(ca) <= 3) {
/* just after backoff */
ca->minB = ca->maxB = ca->Bi = cur_Bi;
} else {
ca->Bi = (3*ca->Bi + cur_Bi)/4;
ca->Bi = (3 * ca->Bi + cur_Bi) / 4;
if (ca->Bi > ca->maxB)
ca->maxB = ca->Bi;
if (ca->minB > ca->maxB)
Expand All @@ -142,15 +148,15 @@ static inline void htcp_beta_update(struct htcp *ca, u32 minRTT, u32 maxRTT)
u32 old_maxB = ca->old_maxB;
ca->old_maxB = ca->maxB;

if (!between(5*maxB, 4*old_maxB, 6*old_maxB)) {
if (!between(5 * maxB, 4 * old_maxB, 6 * old_maxB)) {
ca->beta = BETA_MIN;
ca->modeswitch = 0;
return;
}
}

if (ca->modeswitch && minRTT > msecs_to_jiffies(10) && maxRTT) {
ca->beta = (minRTT<<7)/maxRTT;
ca->beta = (minRTT << 7) / maxRTT;
if (ca->beta < BETA_MIN)
ca->beta = BETA_MIN;
else if (ca->beta > BETA_MAX)
Expand All @@ -169,23 +175,26 @@ static inline void htcp_alpha_update(struct htcp *ca)

if (diff > HZ) {
diff -= HZ;
factor = 1+ ( 10*diff + ((diff/2)*(diff/2)/HZ) )/HZ;
factor = 1 + (10 * diff + ((diff / 2) * (diff / 2) / HZ)) / HZ;
}

if (use_rtt_scaling && minRTT) {
u32 scale = (HZ<<3)/(10*minRTT);
scale = min(max(scale, 1U<<2), 10U<<3); /* clamping ratio to interval [0.5,10]<<3 */
factor = (factor<<3)/scale;
u32 scale = (HZ << 3) / (10 * minRTT);

/* clamping ratio to interval [0.5,10]<<3 */
scale = min(max(scale, 1U << 2), 10U << 3);
factor = (factor << 3) / scale;
if (!factor)
factor = 1;
}

ca->alpha = 2*factor*((1<<7)-ca->beta);
ca->alpha = 2 * factor * ((1 << 7) - ca->beta);
if (!ca->alpha)
ca->alpha = ALPHA_BASE;
}

/* After we have the rtt data to calculate beta, we'd still prefer to wait one
/*
* After we have the rtt data to calculate beta, we'd still prefer to wait one
* rtt before we adjust our beta to ensure we are working from a consistent
* data.
*
Expand All @@ -202,15 +211,16 @@ static void htcp_param_update(struct sock *sk)
htcp_beta_update(ca, minRTT, maxRTT);
htcp_alpha_update(ca);

/* add slowly fading memory for maxRTT to accommodate routing changes etc */
/* add slowly fading memory for maxRTT to accommodate routing changes */
if (minRTT > 0 && maxRTT > minRTT)
ca->maxRTT = minRTT + ((maxRTT-minRTT)*95)/100;
ca->maxRTT = minRTT + ((maxRTT - minRTT) * 95) / 100;
}

static u32 htcp_recalc_ssthresh(struct sock *sk)
{
const struct tcp_sock *tp = tcp_sk(sk);
const struct htcp *ca = inet_csk_ca(sk);

htcp_param_update(sk);
return max((tp->snd_cwnd * ca->beta) >> 7, 2U);
}
Expand All @@ -227,7 +237,6 @@ static void htcp_cong_avoid(struct sock *sk, u32 ack, u32 rtt,
if (tp->snd_cwnd <= tp->snd_ssthresh)
tcp_slow_start(tp);
else {

measure_rtt(sk);

/* In dangerous area, increase slowly.
Expand Down

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