[PATCH 5.10 076/124] tcp: convert elligible sysctls to u8

18 Apr 2023

From: Eric Dumazet edumazet@google.com
[ Upstream commit 4ecc1baf362c5df2dcabe242511e38ee28486545 ]
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
Stable-dep-of: dc5110c2d959 ("tcp: restrict net.ipv4.tcp_app_win")
Signed-off-by: Sasha Levin sashal@kernel.org
---
 include/net/netns/ipv4.h   |  68 +++++++++----------
 net/ipv4/sysctl_net_ipv4.c | 136 ++++++++++++++++++-------------------
 2 files changed, 102 insertions(+), 102 deletions(-)

diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h
index 92e3d8fe954ab..d8b320cf54ba0 100644
--- a/include/net/netns/ipv4.h
+++ b/include/net/netns/ipv4.h
@@ -114,11 +114,11 @@ 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;
@@ -126,46 +126,47 @@ 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;
@@ -183,7 +184,6 @@ 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 cb587bdd683a6..1a2506f795d4e 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -720,17 +720,17 @@ 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,
    },
@@ -738,9 +738,9 @@ 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",
@@ -842,9 +842,9 @@ 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",
@@ -856,26 +856,26 @@ 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
    {
@@ -888,24 +888,24 @@ 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",
@@ -924,9 +924,9 @@ 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,
    },
@@ -1012,88 +1012,88 @@ 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",
@@ -1105,16 +1105,16 @@ 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",
@@ -1128,46 +1128,46 @@ 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",
@@ -1186,9 +1186,9 @@ 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,
    },
@@ -1204,9 +1204,9 @@ 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,
    },
@@ -1277,9 +1277,9 @@ 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,
    },
-- 
2.39.2




    

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[PATCH 5.10 076/124] tcp: convert elligible sysctls to u8