[PATCH net-next 2/2] mptcp: use batch snmp operations in mptcp_seq_show()
flat view
STALE1849d
From: Eric Dumazet <hidden>
Date: 2021-09-30 01:03:43
Subsystem:
networking [general], networking [mptcp], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Matthieu Baerts, Mat Martineau, Linus Torvalds
From: Eric Dumazet <redacted> 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: Eric Dumazet <redacted> --- net/mptcp/mib.c | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-)
diff --git a/net/mptcp/mib.c b/net/mptcp/mib.c
index b21ff9be04c61772c8a7648d9540b48907de9115..3240b72271a7f3724577907bc99bdfe41a97f9de 100644
--- a/net/mptcp/mib.c
+++ b/net/mptcp/mib.c@@ -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'); }
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2.33.0.800.g4c38ced690-goog