diff mbox series

net/ipv4/proc: Avoid usage for seq_printf() when reading /proc/net/snmp

Message ID 20241111045623.10229-1-00107082@163.com (mailing list archive)
State New
Delegated to: Netdev Maintainers
Headers show
Series net/ipv4/proc: Avoid usage for seq_printf() when reading /proc/net/snmp | expand

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netdev/series_format warning Single patches do not need cover letters; Target tree name not specified in the subject
netdev/tree_selection success Guessed tree name to be net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 3 this patch: 3
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers warning 1 maintainers not CCed: horms@kernel.org
netdev/build_clang success Errors and warnings before: 3 this patch: 3
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 4 this patch: 4
netdev/checkpatch warning WARNING: line length of 100 exceeds 80 columns WARNING: line length of 84 exceeds 80 columns WARNING: line length of 85 exceeds 80 columns WARNING: line length of 86 exceeds 80 columns WARNING: line length of 88 exceeds 80 columns WARNING: line length of 89 exceeds 80 columns WARNING: line length of 90 exceeds 80 columns WARNING: line length of 91 exceeds 80 columns WARNING: line length of 92 exceeds 80 columns WARNING: line length of 93 exceeds 80 columns WARNING: line length of 95 exceeds 80 columns WARNING: line length of 97 exceeds 80 columns
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
netdev/contest success net-next-2024-11-11--21-00 (tests: 787)

Commit Message

David Wang Nov. 11, 2024, 4:56 a.m. UTC 
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@163.com>
---
 net/ipv4/proc.c | 116 ++++++++++++++++++++++++++++--------------------
 1 file changed, 69 insertions(+), 47 deletions(-)
diff mbox series

Patch

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');