Commit acbd0c81 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

mptcp: use batch snmp operations in mptcp_seq_show() 



Using snmp_get_cpu_field_batch() allows for better cpu cache
utilization, especially on hosts with large number of cpus.

Also remove special handling when mptcp mibs where not yet
allocated.

I chose to use temporary storage on the stack to keep this patch simple.
We might in the future use the storage allocated in netstat_seq_show().

Combined with prior patch (inlining snmp_get_cpu_field)
time to fetch and output mptcp counters on a 256 cpu host [1]
goes from 75 usec to 16 usec.

[1] L1 cache size is 32KB, it is not big enough to hold all dataset.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 59f09ae8

net/mptcp/mib.c

+7 −10
Original line number Diff line number Diff line
@@ -72,6 +72,7 @@ bool mptcp_mib_alloc(struct net *net) 


void mptcp_seq_show(struct seq_file *seq)

{

	unsigned long sum[ARRAY_SIZE(mptcp_snmp_list) - 1];

	struct net *net = seq->private;

	int i;
@@ -81,17 +82,13 @@ void mptcp_seq_show(struct seq_file *seq) 


	seq_puts(seq, "\nMPTcpExt:");



	if (!net->mib.mptcp_statistics) {

		for (i = 0; mptcp_snmp_list[i].name; i++)

			seq_puts(seq, " 0");



		seq_putc(seq, '\n');

		return;

	}

	memset(sum, 0, sizeof(sum));

	if (net->mib.mptcp_statistics)

		snmp_get_cpu_field_batch(sum, mptcp_snmp_list,

					 net->mib.mptcp_statistics);



	for (i = 0; mptcp_snmp_list[i].name; i++)

		seq_printf(seq, " %lu",

			   snmp_fold_field(net->mib.mptcp_statistics,

					   mptcp_snmp_list[i].entry));

		seq_printf(seq, " %lu", sum[i]);



	seq_putc(seq, '\n');

}