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Message-Id: <20241111045623.10229-1-00107082@163.com>
Date: Mon, 11 Nov 2024 12:56:23 +0800
From: David Wang <00107082@....com>
To: davem@...emloft.net,
dsahern@...nel.org,
edumazet@...gle.com,
kuba@...nel.org,
pabeni@...hat.com
Cc: netdev@...r.kernel.org,
linux-kernel@...r.kernel.org,
David Wang <00107082@....com>
Subject: [PATCH] net/ipv4/proc: Avoid usage for seq_printf() when reading /proc/net/snmp
seq_printf() is costy, when reading /proc/net/snmp, profiling indicates
seq_printf() takes more than 50% samples of snmp_seq_show():
snmp_seq_show(97.751% 158722/162373)
snmp_seq_show_tcp_udp.isra.0(40.017% 63515/158722)
seq_printf(83.451% 53004/63515)
seq_write(1.170% 743/63515)
_find_next_bit(0.727% 462/63515)
...
seq_printf(24.762% 39303/158722)
snmp_seq_show_ipstats.isra.0(21.487% 34104/158722)
seq_printf(85.788% 29257/34104)
_find_next_bit(0.331% 113/34104)
seq_write(0.235% 80/34104)
...
icmpmsg_put(7.235% 11483/158722)
seq_printf(41.714% 4790/11483)
seq_write(2.630% 302/11483)
...
Time for a million rounds of stress reading /proc/net/snmp:
real 0m24.323s
user 0m0.293s
sys 0m23.679s
On average, reading /proc/net/snmp takes 0.023ms.
With this patch, extra costs of seq_printf() is avoided, and a million
rounds of reading /proc/net/snmp now takes only ~15.853s:
real 0m16.386s
user 0m0.280s
sys 0m15.853s
On average, one read takes 0.015ms, a ~40% improvement.
Signed-off-by: David Wang <00107082@....com>
---
net/ipv4/proc.c | 116 ++++++++++++++++++++++++++++--------------------
1 file changed, 69 insertions(+), 47 deletions(-)
diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index 40053a02bae1..3a4586103b5e 100644
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -315,13 +315,14 @@ static void icmpmsg_put_line(struct seq_file *seq, unsigned long *vals,
if (count) {
seq_puts(seq, "\nIcmpMsg:");
- for (j = 0; j < count; ++j)
- seq_printf(seq, " %sType%u",
- type[j] & 0x100 ? "Out" : "In",
- type[j] & 0xff);
+ for (j = 0; j < count; ++j) {
+ seq_putc(seq, ' ');
+ seq_puts(seq, type[j] & 0x100 ? "Out" : "In");
+ seq_put_decimal_ull(seq, "Type", type[j] & 0xff);
+ }
seq_puts(seq, "\nIcmpMsg:");
for (j = 0; j < count; ++j)
- seq_printf(seq, " %lu", vals[j]);
+ seq_put_decimal_ull(seq, " ", vals[j]);
}
}
@@ -358,26 +359,35 @@ static void icmp_put(struct seq_file *seq)
atomic_long_t *ptr = net->mib.icmpmsg_statistics->mibs;
seq_puts(seq, "\nIcmp: InMsgs InErrors InCsumErrors");
- for (i = 0; icmpmibmap[i].name; i++)
- seq_printf(seq, " In%s", icmpmibmap[i].name);
+ for (i = 0; icmpmibmap[i].name; i++) {
+ seq_puts(seq, " In");
+ seq_puts(seq, icmpmibmap[i].name);
+ }
seq_puts(seq, " OutMsgs OutErrors OutRateLimitGlobal OutRateLimitHost");
+ for (i = 0; icmpmibmap[i].name; i++) {
+ seq_puts(seq, " Out");
+ seq_puts(seq, icmpmibmap[i].name);
+ }
+ seq_puts(seq, "\nIcmp:");
+ seq_put_decimal_ull(seq, " ",
+ snmp_fold_field(net->mib.icmp_statistics, ICMP_MIB_INMSGS));
+ seq_put_decimal_ull(seq, " ",
+ snmp_fold_field(net->mib.icmp_statistics, ICMP_MIB_INERRORS));
+ seq_put_decimal_ull(seq, " ",
+ snmp_fold_field(net->mib.icmp_statistics, ICMP_MIB_CSUMERRORS));
for (i = 0; icmpmibmap[i].name; i++)
- seq_printf(seq, " Out%s", icmpmibmap[i].name);
- seq_printf(seq, "\nIcmp: %lu %lu %lu",
- snmp_fold_field(net->mib.icmp_statistics, ICMP_MIB_INMSGS),
- snmp_fold_field(net->mib.icmp_statistics, ICMP_MIB_INERRORS),
- snmp_fold_field(net->mib.icmp_statistics, ICMP_MIB_CSUMERRORS));
+ seq_put_decimal_ull(seq, " ", atomic_long_read(ptr + icmpmibmap[i].index));
+ seq_put_decimal_ull(seq, " ",
+ snmp_fold_field(net->mib.icmp_statistics, ICMP_MIB_OUTMSGS));
+ seq_put_decimal_ull(seq, " ",
+ snmp_fold_field(net->mib.icmp_statistics, ICMP_MIB_OUTERRORS));
+ seq_put_decimal_ull(seq, " ",
+ snmp_fold_field(net->mib.icmp_statistics, ICMP_MIB_RATELIMITGLOBAL));
+ seq_put_decimal_ull(seq, " ",
+ snmp_fold_field(net->mib.icmp_statistics, ICMP_MIB_RATELIMITHOST));
for (i = 0; icmpmibmap[i].name; i++)
- seq_printf(seq, " %lu",
- atomic_long_read(ptr + icmpmibmap[i].index));
- seq_printf(seq, " %lu %lu %lu %lu",
- snmp_fold_field(net->mib.icmp_statistics, ICMP_MIB_OUTMSGS),
- snmp_fold_field(net->mib.icmp_statistics, ICMP_MIB_OUTERRORS),
- snmp_fold_field(net->mib.icmp_statistics, ICMP_MIB_RATELIMITGLOBAL),
- snmp_fold_field(net->mib.icmp_statistics, ICMP_MIB_RATELIMITHOST));
- for (i = 0; icmpmibmap[i].name; i++)
- seq_printf(seq, " %lu",
- atomic_long_read(ptr + (icmpmibmap[i].index | 0x100)));
+ seq_put_decimal_ull(seq, " ",
+ atomic_long_read(ptr + (icmpmibmap[i].index | 0x100)));
}
/*
@@ -392,8 +402,10 @@ static int snmp_seq_show_ipstats(struct seq_file *seq, void *v)
memset(buff64, 0, IPSTATS_MIB_MAX * sizeof(u64));
seq_puts(seq, "Ip: Forwarding DefaultTTL");
- for (i = 0; snmp4_ipstats_list[i].name; i++)
- seq_printf(seq, " %s", snmp4_ipstats_list[i].name);
+ for (i = 0; snmp4_ipstats_list[i].name; i++) {
+ seq_putc(seq, ' ');
+ seq_puts(seq, snmp4_ipstats_list[i].name);
+ }
seq_printf(seq, "\nIp: %d %d",
IPV4_DEVCONF_ALL_RO(net, FORWARDING) ? 1 : 2,
@@ -404,7 +416,7 @@ static int snmp_seq_show_ipstats(struct seq_file *seq, void *v)
net->mib.ip_statistics,
offsetof(struct ipstats_mib, syncp));
for (i = 0; snmp4_ipstats_list[i].name; i++)
- seq_printf(seq, " %llu", buff64[i]);
+ seq_put_decimal_ull(seq, " ", buff64[i]);
return 0;
}
@@ -418,8 +430,10 @@ static int snmp_seq_show_tcp_udp(struct seq_file *seq, void *v)
memset(buff, 0, TCPUDP_MIB_MAX * sizeof(unsigned long));
seq_puts(seq, "\nTcp:");
- for (i = 0; snmp4_tcp_list[i].name; i++)
- seq_printf(seq, " %s", snmp4_tcp_list[i].name);
+ for (i = 0; snmp4_tcp_list[i].name; i++) {
+ seq_putc(seq, ' ');
+ seq_puts(seq, snmp4_tcp_list[i].name);
+ }
seq_puts(seq, "\nTcp:");
snmp_get_cpu_field_batch(buff, snmp4_tcp_list,
@@ -429,7 +443,7 @@ static int snmp_seq_show_tcp_udp(struct seq_file *seq, void *v)
if (snmp4_tcp_list[i].entry == TCP_MIB_MAXCONN)
seq_printf(seq, " %ld", buff[i]);
else
- seq_printf(seq, " %lu", buff[i]);
+ seq_put_decimal_ull(seq, " ", buff[i]);
}
memset(buff, 0, TCPUDP_MIB_MAX * sizeof(unsigned long));
@@ -437,11 +451,13 @@ static int snmp_seq_show_tcp_udp(struct seq_file *seq, void *v)
snmp_get_cpu_field_batch(buff, snmp4_udp_list,
net->mib.udp_statistics);
seq_puts(seq, "\nUdp:");
- for (i = 0; snmp4_udp_list[i].name; i++)
- seq_printf(seq, " %s", snmp4_udp_list[i].name);
+ for (i = 0; snmp4_udp_list[i].name; i++) {
+ seq_putc(seq, ' ');
+ seq_puts(seq, snmp4_udp_list[i].name);
+ }
seq_puts(seq, "\nUdp:");
for (i = 0; snmp4_udp_list[i].name; i++)
- seq_printf(seq, " %lu", buff[i]);
+ seq_put_decimal_ull(seq, " ", buff[i]);
memset(buff, 0, TCPUDP_MIB_MAX * sizeof(unsigned long));
@@ -449,11 +465,13 @@ static int snmp_seq_show_tcp_udp(struct seq_file *seq, void *v)
seq_puts(seq, "\nUdpLite:");
snmp_get_cpu_field_batch(buff, snmp4_udp_list,
net->mib.udplite_statistics);
- for (i = 0; snmp4_udp_list[i].name; i++)
- seq_printf(seq, " %s", snmp4_udp_list[i].name);
+ for (i = 0; snmp4_udp_list[i].name; i++) {
+ seq_putc(seq, ' ');
+ seq_puts(seq, snmp4_udp_list[i].name);
+ }
seq_puts(seq, "\nUdpLite:");
for (i = 0; snmp4_udp_list[i].name; i++)
- seq_printf(seq, " %lu", buff[i]);
+ seq_put_decimal_ull(seq, " ", buff[i]);
seq_putc(seq, '\n');
return 0;
@@ -483,8 +501,10 @@ static int netstat_seq_show(struct seq_file *seq, void *v)
int i;
seq_puts(seq, "TcpExt:");
- for (i = 0; i < tcp_cnt; i++)
- seq_printf(seq, " %s", snmp4_net_list[i].name);
+ for (i = 0; i < tcp_cnt; i++) {
+ seq_putc(seq, ' ');
+ seq_puts(seq, snmp4_net_list[i].name);
+ }
seq_puts(seq, "\nTcpExt:");
buff = kzalloc(max(tcp_cnt * sizeof(long), ip_cnt * sizeof(u64)),
@@ -493,16 +513,18 @@ static int netstat_seq_show(struct seq_file *seq, void *v)
snmp_get_cpu_field_batch(buff, snmp4_net_list,
net->mib.net_statistics);
for (i = 0; i < tcp_cnt; i++)
- seq_printf(seq, " %lu", buff[i]);
+ seq_put_decimal_ull(seq, " ", buff[i]);
} else {
for (i = 0; i < tcp_cnt; i++)
- seq_printf(seq, " %lu",
- snmp_fold_field(net->mib.net_statistics,
- snmp4_net_list[i].entry));
+ seq_put_decimal_ull(seq, " ",
+ snmp_fold_field(net->mib.net_statistics,
+ snmp4_net_list[i].entry));
}
seq_puts(seq, "\nIpExt:");
- for (i = 0; i < ip_cnt; i++)
- seq_printf(seq, " %s", snmp4_ipextstats_list[i].name);
+ for (i = 0; i < ip_cnt; i++) {
+ seq_putc(seq, ' ');
+ seq_puts(seq, snmp4_ipextstats_list[i].name);
+ }
seq_puts(seq, "\nIpExt:");
if (buff) {
@@ -513,13 +535,13 @@ static int netstat_seq_show(struct seq_file *seq, void *v)
net->mib.ip_statistics,
offsetof(struct ipstats_mib, syncp));
for (i = 0; i < ip_cnt; i++)
- seq_printf(seq, " %llu", buff64[i]);
+ seq_put_decimal_ull(seq, " ", buff64[i]);
} else {
for (i = 0; i < ip_cnt; i++)
- seq_printf(seq, " %llu",
- snmp_fold_field64(net->mib.ip_statistics,
- snmp4_ipextstats_list[i].entry,
- offsetof(struct ipstats_mib, syncp)));
+ seq_put_decimal_ull(seq, " ",
+ snmp_fold_field64(net->mib.ip_statistics,
+ snmp4_ipextstats_list[i].entry,
+ offsetof(struct ipstats_mib, syncp)));
}
kfree(buff);
seq_putc(seq, '\n');
--
2.39.2
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