Re: [PATCH RFC V3 2/2] net: Optimize snmp stat aggregation by walking all the percpu data at once

From: Eric Dumazet
Date: Sat Aug 29 2015 - 10:32:15 EST

On Sat, 2015-08-29 at 14:37 +0530, Raghavendra K T wrote:

> static inline void __snmp6_fill_stats64(u64 *stats, void __percpu *mib,
> - int items, int bytes, size_t syncpoff)
> + int items, int bytes, size_t syncpoff)
> {
> - int i;
> + int i, c;
> int pad = bytes - sizeof(u64) * items;
> + u64 buff[items];
> +

One last comment : using variable length arrays is confusing for the
reader, and sparse as well.

$ make C=2 net/ipv6/addrconf.o
CHECK net/ipv6/addrconf.c
net/ipv6/addrconf.c:4733:18: warning: Variable length array is used.
net/ipv6/addrconf.c:4737:25: error: cannot size expression

I suggest you remove 'items' parameter and replace it by
IPSTATS_MIB_MAX, as __snmp6_fill_stats64() is called exactly once.

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