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linux/include/net/snmp.h
Eric Dumazet 2a24444f8f ipv6: reduce percpu needs for icmpv6msg mibs 
Reading /proc/net/snmp6 on a machine with a lot of cpus is very
expensive (can be ~88000 us).

This is because ICMPV6MSG MIB uses 4096 bytes per cpu, and folding
values for all possible cpus can read 16 Mbytes of memory (32MBytes on
non x86 arches)

ICMP messages are not considered as fast path on a typical server, and
eventually few cpus handle them anyway. We can afford an atomic
operation instead of using percpu data.

This saves 4096 bytes per cpu and per network namespace.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2011-11-14 00:12:26 -05:00

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/*
*
* SNMP MIB entries for the IP subsystem.
*
* Alan Cox <gw4pts@gw4pts.ampr.org>
*
* We don't chose to implement SNMP in the kernel (this would
* be silly as SNMP is a pain in the backside in places). We do
* however need to collect the MIB statistics and export them
* out of /proc (eventually)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
*/
#ifndef _SNMP_H
#define _SNMP_H
#include <linux/cache.h>
#include <linux/snmp.h>
#include <linux/smp.h>
/*
* Mibs are stored in array of unsigned long.
*/
/*
* struct snmp_mib{}
* - list of entries for particular API (such as /proc/net/snmp)
* - name of entries.
*/
struct snmp_mib {
const char *name;
int entry;
};
#define SNMP_MIB_ITEM(_name,_entry) { \
.name = _name, \
.entry = _entry, \
}
#define SNMP_MIB_SENTINEL { \
.name = NULL, \
.entry = 0, \
}
/*
* We use unsigned longs for most mibs but u64 for ipstats.
*/
#include <linux/u64_stats_sync.h>
/* IPstats */
#define IPSTATS_MIB_MAX __IPSTATS_MIB_MAX
struct ipstats_mib {
/* mibs[] must be first field of struct ipstats_mib */
u64 mibs[IPSTATS_MIB_MAX];
struct u64_stats_sync syncp;
};
/* ICMP */
#define ICMP_MIB_MAX __ICMP_MIB_MAX
struct icmp_mib {
unsigned long mibs[ICMP_MIB_MAX];
};
#define ICMPMSG_MIB_MAX __ICMPMSG_MIB_MAX
struct icmpmsg_mib {
atomic_long_t mibs[ICMPMSG_MIB_MAX];
};
/* ICMP6 (IPv6-ICMP) */
#define ICMP6_MIB_MAX __ICMP6_MIB_MAX
/* per network ns counters */
struct icmpv6_mib {
unsigned long mibs[ICMP6_MIB_MAX];
};
/* per device counters, (shared on all cpus) */
struct icmpv6_mib_device {
atomic_long_t mibs[ICMP6_MIB_MAX];
};
#define ICMP6MSG_MIB_MAX __ICMP6MSG_MIB_MAX
/* per network ns counters */
struct icmpv6msg_mib {
atomic_long_t mibs[ICMP6MSG_MIB_MAX];
};
/* per device counters, (shared on all cpus) */
struct icmpv6msg_mib_device {
atomic_long_t mibs[ICMP6MSG_MIB_MAX];
};
/* TCP */
#define TCP_MIB_MAX __TCP_MIB_MAX
struct tcp_mib {
unsigned long mibs[TCP_MIB_MAX];
};
/* UDP */
#define UDP_MIB_MAX __UDP_MIB_MAX
struct udp_mib {
unsigned long mibs[UDP_MIB_MAX];
};
/* Linux */
#define LINUX_MIB_MAX __LINUX_MIB_MAX
struct linux_mib {
unsigned long mibs[LINUX_MIB_MAX];
};
/* Linux Xfrm */
#define LINUX_MIB_XFRMMAX __LINUX_MIB_XFRMMAX
struct linux_xfrm_mib {
unsigned long mibs[LINUX_MIB_XFRMMAX];
};
#define SNMP_ARRAY_SZ 1
#define DEFINE_SNMP_STAT(type, name) \
__typeof__(type) __percpu *name[SNMP_ARRAY_SZ]
#define DEFINE_SNMP_STAT_ATOMIC(type, name) \
__typeof__(type) *name
#define DECLARE_SNMP_STAT(type, name) \
extern __typeof__(type) __percpu *name[SNMP_ARRAY_SZ]
#define SNMP_INC_STATS_BH(mib, field) \
__this_cpu_inc(mib[0]->mibs[field])
#define SNMP_INC_STATS_USER(mib, field) \
irqsafe_cpu_inc(mib[0]->mibs[field])
#define SNMP_INC_STATS_ATOMIC_LONG(mib, field) \
atomic_long_inc(&mib->mibs[field])
#define SNMP_INC_STATS(mib, field) \
irqsafe_cpu_inc(mib[0]->mibs[field])
#define SNMP_DEC_STATS(mib, field) \
irqsafe_cpu_dec(mib[0]->mibs[field])
#define SNMP_ADD_STATS_BH(mib, field, addend) \
__this_cpu_add(mib[0]->mibs[field], addend)
#define SNMP_ADD_STATS_USER(mib, field, addend) \
irqsafe_cpu_add(mib[0]->mibs[field], addend)
#define SNMP_ADD_STATS(mib, field, addend) \
irqsafe_cpu_add(mib[0]->mibs[field], addend)
/*
* Use "__typeof__(*mib[0]) *ptr" instead of "__typeof__(mib[0]) ptr"
* to make @ptr a non-percpu pointer.
*/
#define SNMP_UPD_PO_STATS(mib, basefield, addend) \
do { \
irqsafe_cpu_inc(mib[0]->mibs[basefield##PKTS]); \
irqsafe_cpu_add(mib[0]->mibs[basefield##OCTETS], addend); \
} while (0)
#define SNMP_UPD_PO_STATS_BH(mib, basefield, addend) \
do { \
__this_cpu_inc(mib[0]->mibs[basefield##PKTS]); \
__this_cpu_add(mib[0]->mibs[basefield##OCTETS], addend); \
} while (0)
#if BITS_PER_LONG==32
#define SNMP_ADD_STATS64_BH(mib, field, addend) \
do { \
__typeof__(*mib[0]) *ptr = __this_cpu_ptr((mib)[0]); \
u64_stats_update_begin(&ptr->syncp); \
ptr->mibs[field] += addend; \
u64_stats_update_end(&ptr->syncp); \
} while (0)
#define SNMP_ADD_STATS64_USER(mib, field, addend) \
do { \
local_bh_disable(); \
SNMP_ADD_STATS64_BH(mib, field, addend); \
local_bh_enable(); \
} while (0)
#define SNMP_ADD_STATS64(mib, field, addend) \
SNMP_ADD_STATS64_USER(mib, field, addend)
#define SNMP_INC_STATS64_BH(mib, field) SNMP_ADD_STATS64_BH(mib, field, 1)
#define SNMP_INC_STATS64_USER(mib, field) SNMP_ADD_STATS64_USER(mib, field, 1)
#define SNMP_INC_STATS64(mib, field) SNMP_ADD_STATS64(mib, field, 1)
#define SNMP_UPD_PO_STATS64_BH(mib, basefield, addend) \
do { \
__typeof__(*mib[0]) *ptr; \
ptr = __this_cpu_ptr((mib)[0]); \
u64_stats_update_begin(&ptr->syncp); \
ptr->mibs[basefield##PKTS]++; \
ptr->mibs[basefield##OCTETS] += addend; \
u64_stats_update_end(&ptr->syncp); \
} while (0)
#define SNMP_UPD_PO_STATS64(mib, basefield, addend) \
do { \
local_bh_disable(); \
SNMP_UPD_PO_STATS64_BH(mib, basefield, addend); \
local_bh_enable(); \
} while (0)
#else
#define SNMP_INC_STATS64_BH(mib, field) SNMP_INC_STATS_BH(mib, field)
#define SNMP_INC_STATS64_USER(mib, field) SNMP_INC_STATS_USER(mib, field)
#define SNMP_INC_STATS64(mib, field) SNMP_INC_STATS(mib, field)
#define SNMP_DEC_STATS64(mib, field) SNMP_DEC_STATS(mib, field)
#define SNMP_ADD_STATS64_BH(mib, field, addend) SNMP_ADD_STATS_BH(mib, field, addend)
#define SNMP_ADD_STATS64_USER(mib, field, addend) SNMP_ADD_STATS_USER(mib, field, addend)
#define SNMP_ADD_STATS64(mib, field, addend) SNMP_ADD_STATS(mib, field, addend)
#define SNMP_UPD_PO_STATS64(mib, basefield, addend) SNMP_UPD_PO_STATS(mib, basefield, addend)
#define SNMP_UPD_PO_STATS64_BH(mib, basefield, addend) SNMP_UPD_PO_STATS_BH(mib, basefield, addend)
#endif
#endif
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