proc: Reduce cache miss in snmp_seq_show

This is to use the generic interfaces snmp_get_cpu_field{,64}_batch to
aggregate the data by going through all the items of each cpu sequentially.
Then snmp_seq_show is split into 2 parts to avoid build warning "the frame
size" larger than 1024.

Signed-off-by: Jia He <hejianet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index 1ed015e..f51fc88 100644 (file)
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -46,6 +46,8 @@
 #include <net/sock.h>
 #include <net/raw.h>
 
+#define TCPUDP_MIB_MAX max_t(u32, UDP_MIB_MAX, TCP_MIB_MAX)
+
 /*
  *     Report socket allocation statistics [mea@utu.fi]
  */
@@ -379,13 +381,15 @@ static void icmp_put(struct seq_file *seq)
 /*
  *     Called from the PROCfs module. This outputs /proc/net/snmp.
  */
-static int snmp_seq_show(struct seq_file *seq, void *v)
+static int snmp_seq_show_ipstats(struct seq_file *seq, void *v)
 {
-       int i;
        struct net *net = seq->private;
+       u64 buff64[IPSTATS_MIB_MAX];
+       int i;
 
-       seq_puts(seq, "Ip: Forwarding DefaultTTL");
+       memset(buff64, 0, IPSTATS_MIB_MAX * sizeof(u64));
 
+       seq_puts(seq, "Ip: Forwarding DefaultTTL");
        for (i = 0; snmp4_ipstats_list[i].name != NULL; i++)
                seq_printf(seq, " %s", snmp4_ipstats_list[i].name);
 
@@ -394,57 +398,77 @@ static int snmp_seq_show(struct seq_file *seq, void *v)
                   net->ipv4.sysctl_ip_default_ttl);
 
        BUILD_BUG_ON(offsetof(struct ipstats_mib, mibs) != 0);
+       snmp_get_cpu_field64_batch(buff64, snmp4_ipstats_list,
+                                  net->mib.ip_statistics,
+                                  offsetof(struct ipstats_mib, syncp));
        for (i = 0; snmp4_ipstats_list[i].name != NULL; i++)
-               seq_printf(seq, " %llu",
-                          snmp_fold_field64(net->mib.ip_statistics,
-                                            snmp4_ipstats_list[i].entry,
-                                            offsetof(struct ipstats_mib, syncp)));
+               seq_printf(seq, " %llu", buff64[i]);
 
-       icmp_put(seq);  /* RFC 2011 compatibility */
-       icmpmsg_put(seq);
+       return 0;
+}
+
+static int snmp_seq_show_tcp_udp(struct seq_file *seq, void *v)
+{
+       unsigned long buff[TCPUDP_MIB_MAX];
+       struct net *net = seq->private;
+       int i;
+
+       memset(buff, 0, TCPUDP_MIB_MAX * sizeof(unsigned long));
 
        seq_puts(seq, "\nTcp:");
        for (i = 0; snmp4_tcp_list[i].name != NULL; i++)
                seq_printf(seq, " %s", snmp4_tcp_list[i].name);
 
        seq_puts(seq, "\nTcp:");
+       snmp_get_cpu_field_batch(buff, snmp4_tcp_list,
+                                net->mib.tcp_statistics);
        for (i = 0; snmp4_tcp_list[i].name != NULL; i++) {
                /* MaxConn field is signed, RFC 2012 */
                if (snmp4_tcp_list[i].entry == TCP_MIB_MAXCONN)
-                       seq_printf(seq, " %ld",
-                                  snmp_fold_field(net->mib.tcp_statistics,
-                                                  snmp4_tcp_list[i].entry));
+                       seq_printf(seq, " %ld", buff[i]);
                else
-                       seq_printf(seq, " %lu",
-                                  snmp_fold_field(net->mib.tcp_statistics,
-                                                  snmp4_tcp_list[i].entry));
+                       seq_printf(seq, " %lu", buff[i]);
        }
 
+       memset(buff, 0, TCPUDP_MIB_MAX * sizeof(unsigned long));
+
+       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 != NULL; i++)
                seq_printf(seq, " %s", snmp4_udp_list[i].name);
-
        seq_puts(seq, "\nUdp:");
        for (i = 0; snmp4_udp_list[i].name != NULL; i++)
-               seq_printf(seq, " %lu",
-                          snmp_fold_field(net->mib.udp_statistics,
-                                          snmp4_udp_list[i].entry));
+               seq_printf(seq, " %lu", buff[i]);
+
+       memset(buff, 0, TCPUDP_MIB_MAX * sizeof(unsigned long));
 
        /* the UDP and UDP-Lite MIBs are the same */
        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 != NULL; i++)
                seq_printf(seq, " %s", snmp4_udp_list[i].name);
-
        seq_puts(seq, "\nUdpLite:");
        for (i = 0; snmp4_udp_list[i].name != NULL; i++)
-               seq_printf(seq, " %lu",
-                          snmp_fold_field(net->mib.udplite_statistics,
-                                          snmp4_udp_list[i].entry));
+               seq_printf(seq, " %lu", buff[i]);
 
        seq_putc(seq, '\n');
        return 0;
 }
 
+static int snmp_seq_show(struct seq_file *seq, void *v)
+{
+       snmp_seq_show_ipstats(seq, v);
+
+       icmp_put(seq);  /* RFC 2011 compatibility */
+       icmpmsg_put(seq);
+
+       snmp_seq_show_tcp_udp(seq, v);
+
+       return 0;
+}
+
 static int snmp_seq_open(struct inode *inode, struct file *file)
 {
        return single_open_net(inode, file, snmp_seq_show);