tcp: convert elligible sysctls to u8

Many tcp sysctls are either bools or small ints that can fit into u8.

Reducing space taken by sysctls can save few cache line misses
when sending/receiving data while cpu caches are empty,
for example after cpu idle period.

This is hard to measure with typical network performance tests,
but after this patch, struct netns_ipv4 has shrunk
by three cache lines.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 102 insertions, 102 deletions

diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h
index 00f250ee4419..d377266d133f 100644
--- a/include/net/netns/ipv4.h
+++ b/include/net/netns/ipv4.h
@@ -113,11 +113,11 @@ struct netns_ipv4 {
 	u8 sysctl_nexthop_compat_mode;
 
 	u8 sysctl_fwmark_reflect;
-	int sysctl_tcp_fwmark_accept;
+	u8 sysctl_tcp_fwmark_accept;
 #ifdef CONFIG_NET_L3_MASTER_DEV
-	int sysctl_tcp_l3mdev_accept;
+	u8 sysctl_tcp_l3mdev_accept;
 #endif
-	int sysctl_tcp_mtu_probing;
+	u8 sysctl_tcp_mtu_probing;
 	int sysctl_tcp_mtu_probe_floor;
 	int sysctl_tcp_base_mss;
 	int sysctl_tcp_min_snd_mss;
@@ -125,46 +125,47 @@ struct netns_ipv4 {
 	u32 sysctl_tcp_probe_interval;
 
 	int sysctl_tcp_keepalive_time;
-	int sysctl_tcp_keepalive_probes;
 	int sysctl_tcp_keepalive_intvl;
+	u8 sysctl_tcp_keepalive_probes;
 
-	int sysctl_tcp_syn_retries;
-	int sysctl_tcp_synack_retries;
-	int sysctl_tcp_syncookies;
+	u8 sysctl_tcp_syn_retries;
+	u8 sysctl_tcp_synack_retries;
+	u8 sysctl_tcp_syncookies;
 	int sysctl_tcp_reordering;
-	int sysctl_tcp_retries1;
-	int sysctl_tcp_retries2;
-	int sysctl_tcp_orphan_retries;
+	u8 sysctl_tcp_retries1;
+	u8 sysctl_tcp_retries2;
+	u8 sysctl_tcp_orphan_retries;
+	u8 sysctl_tcp_tw_reuse;
 	int sysctl_tcp_fin_timeout;
 	unsigned int sysctl_tcp_notsent_lowat;
-	int sysctl_tcp_tw_reuse;
-	int sysctl_tcp_sack;
-	int sysctl_tcp_window_scaling;
-	int sysctl_tcp_timestamps;
-	int sysctl_tcp_early_retrans;
-	int sysctl_tcp_recovery;
-	int sysctl_tcp_thin_linear_timeouts;
-	int sysctl_tcp_slow_start_after_idle;
-	int sysctl_tcp_retrans_collapse;
-	int sysctl_tcp_stdurg;
-	int sysctl_tcp_rfc1337;
-	int sysctl_tcp_abort_on_overflow;
-	int sysctl_tcp_fack;
+	u8 sysctl_tcp_sack;
+	u8 sysctl_tcp_window_scaling;
+	u8 sysctl_tcp_timestamps;
+	u8 sysctl_tcp_early_retrans;
+	u8 sysctl_tcp_recovery;
+	u8 sysctl_tcp_thin_linear_timeouts;
+	u8 sysctl_tcp_slow_start_after_idle;
+	u8 sysctl_tcp_retrans_collapse;
+	u8 sysctl_tcp_stdurg;
+	u8 sysctl_tcp_rfc1337;
+	u8 sysctl_tcp_abort_on_overflow;
+	u8 sysctl_tcp_fack; /* obsolete */
 	int sysctl_tcp_max_reordering;
-	int sysctl_tcp_dsack;
-	int sysctl_tcp_app_win;
 	int sysctl_tcp_adv_win_scale;
-	int sysctl_tcp_frto;
-	int sysctl_tcp_nometrics_save;
-	int sysctl_tcp_no_ssthresh_metrics_save;
-	int sysctl_tcp_moderate_rcvbuf;
-	int sysctl_tcp_tso_win_divisor;
-	int sysctl_tcp_workaround_signed_windows;
+	u8 sysctl_tcp_dsack;
+	u8 sysctl_tcp_app_win;
+	u8 sysctl_tcp_frto;
+	u8 sysctl_tcp_nometrics_save;
+	u8 sysctl_tcp_no_ssthresh_metrics_save;
+	u8 sysctl_tcp_moderate_rcvbuf;
+	u8 sysctl_tcp_tso_win_divisor;
+	u8 sysctl_tcp_workaround_signed_windows;
 	int sysctl_tcp_limit_output_bytes;
 	int sysctl_tcp_challenge_ack_limit;
-	int sysctl_tcp_min_tso_segs;
 	int sysctl_tcp_min_rtt_wlen;
-	int sysctl_tcp_autocorking;
+	u8 sysctl_tcp_min_tso_segs;
+	u8 sysctl_tcp_autocorking;
+	u8 sysctl_tcp_reflect_tos;
 	int sysctl_tcp_invalid_ratelimit;
 	int sysctl_tcp_pacing_ss_ratio;
 	int sysctl_tcp_pacing_ca_ratio;
@@ -182,7 +183,6 @@ struct netns_ipv4 {
 	unsigned int sysctl_tcp_fastopen_blackhole_timeout;
 	atomic_t tfo_active_disable_times;
 	unsigned long tfo_active_disable_stamp;
-	int sysctl_tcp_reflect_tos;
 
 	int sysctl_udp_wmem_min;
 	int sysctl_udp_rmem_min;
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 510a32635612..442ff4be1bde 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -775,17 +775,17 @@ static struct ctl_table ipv4_net_table[] = {
 	{
 		.procname	= "tcp_fwmark_accept",
 		.data		= &init_net.ipv4.sysctl_tcp_fwmark_accept,
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(u8),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec,
+		.proc_handler	= proc_dou8vec_minmax,
 	},
 #ifdef CONFIG_NET_L3_MASTER_DEV
 	{
 		.procname	= "tcp_l3mdev_accept",
 		.data		= &init_net.ipv4.sysctl_tcp_l3mdev_accept,
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(u8),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
+		.proc_handler	= proc_dou8vec_minmax,
 		.extra1		= SYSCTL_ZERO,
 		.extra2		= SYSCTL_ONE,
 	},
@@ -793,9 +793,9 @@ static struct ctl_table ipv4_net_table[] = {
 	{
 		.procname	= "tcp_mtu_probing",
 		.data		= &init_net.ipv4.sysctl_tcp_mtu_probing,
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(u8),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec,
+		.proc_handler	= proc_dou8vec_minmax,
 	},
 	{
 		.procname	= "tcp_base_mss",
@@ -897,9 +897,9 @@ static struct ctl_table ipv4_net_table[] = {
 	{
 		.procname	= "tcp_keepalive_probes",
 		.data		= &init_net.ipv4.sysctl_tcp_keepalive_probes,
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(u8),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec
+		.proc_handler	= proc_dou8vec_minmax,
 	},
 	{
 		.procname	= "tcp_keepalive_intvl",
@@ -911,26 +911,26 @@ static struct ctl_table ipv4_net_table[] = {
 	{
 		.procname	= "tcp_syn_retries",
 		.data		= &init_net.ipv4.sysctl_tcp_syn_retries,
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(u8),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
+		.proc_handler	= proc_dou8vec_minmax,
 		.extra1		= &tcp_syn_retries_min,
 		.extra2		= &tcp_syn_retries_max
 	},
 	{
 		.procname	= "tcp_synack_retries",
 		.data		= &init_net.ipv4.sysctl_tcp_synack_retries,
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(u8),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec
+		.proc_handler	= proc_dou8vec_minmax,
 	},
 #ifdef CONFIG_SYN_COOKIES
 	{
 		.procname	= "tcp_syncookies",
 		.data		= &init_net.ipv4.sysctl_tcp_syncookies,
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(u8),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec
+		.proc_handler	= proc_dou8vec_minmax,
 	},
 #endif
 	{
@@ -943,24 +943,24 @@ static struct ctl_table ipv4_net_table[] = {
 	{
 		.procname	= "tcp_retries1",
 		.data		= &init_net.ipv4.sysctl_tcp_retries1,
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(u8),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
+		.proc_handler	= proc_dou8vec_minmax,
 		.extra2		= &tcp_retr1_max
 	},
 	{
 		.procname	= "tcp_retries2",
 		.data		= &init_net.ipv4.sysctl_tcp_retries2,
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(u8),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec
+		.proc_handler	= proc_dou8vec_minmax,
 	},
 	{
 		.procname	= "tcp_orphan_retries",
 		.data		= &init_net.ipv4.sysctl_tcp_orphan_retries,
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(u8),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec
+		.proc_handler	= proc_dou8vec_minmax,
 	},
 	{
 		.procname	= "tcp_fin_timeout",
@@ -979,9 +979,9 @@ static struct ctl_table ipv4_net_table[] = {
 	{
 		.procname	= "tcp_tw_reuse",
 		.data		= &init_net.ipv4.sysctl_tcp_tw_reuse,
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(u8),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
+		.proc_handler	= proc_dou8vec_minmax,
 		.extra1		= SYSCTL_ZERO,
 		.extra2		= &two,
 	},
@@ -1067,88 +1067,88 @@ static struct ctl_table ipv4_net_table[] = {
 	{
 		.procname	= "tcp_sack",
 		.data		= &init_net.ipv4.sysctl_tcp_sack,
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(u8),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec
+		.proc_handler	= proc_dou8vec_minmax,
 	},
 	{
 		.procname	= "tcp_window_scaling",
 		.data		= &init_net.ipv4.sysctl_tcp_window_scaling,
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(u8),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec
+		.proc_handler	= proc_dou8vec_minmax,
 	},
 	{
 		.procname	= "tcp_timestamps",
 		.data		= &init_net.ipv4.sysctl_tcp_timestamps,
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(u8),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec
+		.proc_handler	= proc_dou8vec_minmax,
 	},
 	{
 		.procname	= "tcp_early_retrans",
 		.data		= &init_net.ipv4.sysctl_tcp_early_retrans,
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(u8),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
+		.proc_handler	= proc_dou8vec_minmax,
 		.extra1		= SYSCTL_ZERO,
 		.extra2		= &four,
 	},
 	{
 		.procname	= "tcp_recovery",
 		.data		= &init_net.ipv4.sysctl_tcp_recovery,
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(u8),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec,
+		.proc_handler	= proc_dou8vec_minmax,
 	},
 	{
 		.procname       = "tcp_thin_linear_timeouts",
 		.data           = &init_net.ipv4.sysctl_tcp_thin_linear_timeouts,
-		.maxlen         = sizeof(int),
+		.maxlen         = sizeof(u8),
 		.mode           = 0644,
-		.proc_handler   = proc_dointvec
+		.proc_handler   = proc_dou8vec_minmax,
 	},
 	{
 		.procname	= "tcp_slow_start_after_idle",
 		.data		= &init_net.ipv4.sysctl_tcp_slow_start_after_idle,
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(u8),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec
+		.proc_handler	= proc_dou8vec_minmax,
 	},
 	{
 		.procname	= "tcp_retrans_collapse",
 		.data		= &init_net.ipv4.sysctl_tcp_retrans_collapse,
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(u8),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec
+		.proc_handler	= proc_dou8vec_minmax,
 	},
 	{
 		.procname	= "tcp_stdurg",
 		.data		= &init_net.ipv4.sysctl_tcp_stdurg,
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(u8),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec
+		.proc_handler	= proc_dou8vec_minmax,
 	},
 	{
 		.procname	= "tcp_rfc1337",
 		.data		= &init_net.ipv4.sysctl_tcp_rfc1337,
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(u8),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec
+		.proc_handler	= proc_dou8vec_minmax,
 	},
 	{
 		.procname	= "tcp_abort_on_overflow",
 		.data		= &init_net.ipv4.sysctl_tcp_abort_on_overflow,
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(u8),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec
+		.proc_handler	= proc_dou8vec_minmax,
 	},
 	{
 		.procname	= "tcp_fack",
 		.data		= &init_net.ipv4.sysctl_tcp_fack,
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(u8),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec
+		.proc_handler	= proc_dou8vec_minmax,
 	},
 	{
 		.procname	= "tcp_max_reordering",
@@ -1160,16 +1160,16 @@ static struct ctl_table ipv4_net_table[] = {
 	{
 		.procname	= "tcp_dsack",
 		.data		= &init_net.ipv4.sysctl_tcp_dsack,
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(u8),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec
+		.proc_handler	= proc_dou8vec_minmax,
 	},
 	{
 		.procname	= "tcp_app_win",
 		.data		= &init_net.ipv4.sysctl_tcp_app_win,
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(u8),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec
+		.proc_handler	= proc_dou8vec_minmax,
 	},
 	{
 		.procname	= "tcp_adv_win_scale",
@@ -1183,46 +1183,46 @@ static struct ctl_table ipv4_net_table[] = {
 	{
 		.procname	= "tcp_frto",
 		.data		= &init_net.ipv4.sysctl_tcp_frto,
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(u8),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec
+		.proc_handler	= proc_dou8vec_minmax,
 	},
 	{
 		.procname	= "tcp_no_metrics_save",
 		.data		= &init_net.ipv4.sysctl_tcp_nometrics_save,
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(u8),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec,
+		.proc_handler	= proc_dou8vec_minmax,
 	},
 	{
 		.procname	= "tcp_no_ssthresh_metrics_save",
 		.data		= &init_net.ipv4.sysctl_tcp_no_ssthresh_metrics_save,
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(u8),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
+		.proc_handler	= proc_dou8vec_minmax,
 		.extra1		= SYSCTL_ZERO,
 		.extra2		= SYSCTL_ONE,
 	},
 	{
 		.procname	= "tcp_moderate_rcvbuf",
 		.data		= &init_net.ipv4.sysctl_tcp_moderate_rcvbuf,
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(u8),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec,
+		.proc_handler	= proc_dou8vec_minmax,
 	},
 	{
 		.procname	= "tcp_tso_win_divisor",
 		.data		= &init_net.ipv4.sysctl_tcp_tso_win_divisor,
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(u8),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec,
+		.proc_handler	= proc_dou8vec_minmax,
 	},
 	{
 		.procname	= "tcp_workaround_signed_windows",
 		.data		= &init_net.ipv4.sysctl_tcp_workaround_signed_windows,
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(u8),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec
+		.proc_handler	= proc_dou8vec_minmax,
 	},
 	{
 		.procname	= "tcp_limit_output_bytes",
@@ -1241,9 +1241,9 @@ static struct ctl_table ipv4_net_table[] = {
 	{
 		.procname	= "tcp_min_tso_segs",
 		.data		= &init_net.ipv4.sysctl_tcp_min_tso_segs,
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(u8),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
+		.proc_handler	= proc_dou8vec_minmax,
 		.extra1		= SYSCTL_ONE,
 		.extra2		= &gso_max_segs,
 	},
@@ -1259,9 +1259,9 @@ static struct ctl_table ipv4_net_table[] = {
 	{
 		.procname	= "tcp_autocorking",
 		.data		= &init_net.ipv4.sysctl_tcp_autocorking,
-		.maxlen		= sizeof(int),
+		.maxlen		= sizeof(u8),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
+		.proc_handler	= proc_dou8vec_minmax,
 		.extra1		= SYSCTL_ZERO,
 		.extra2		= SYSCTL_ONE,
 	},
@@ -1332,9 +1332,9 @@ static struct ctl_table ipv4_net_table[] = {
 	{
 		.procname       = "tcp_reflect_tos",
 		.data           = &init_net.ipv4.sysctl_tcp_reflect_tos,
-		.maxlen         = sizeof(int),
+		.maxlen         = sizeof(u8),
 		.mode           = 0644,
-		.proc_handler   = proc_dointvec_minmax,
+		.proc_handler   = proc_dou8vec_minmax,
 		.extra1         = SYSCTL_ZERO,
 		.extra2         = SYSCTL_ONE,
 	},