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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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81c3d5470e
Arnaldo and I agreed it could be applied now, because I have other
pending patches depending on this one (Thank you Arnaldo)
(The other important patch moves skc_refcnt in a separate cache line,
so that the SMP/NUMA performance doesnt suffer from cache line ping pongs)
1) First some performance data :
--------------------------------
tcp_v4_rcv() wastes a *lot* of time in __inet_lookup_established()
The most time critical code is :
sk_for_each(sk, node, &head->chain) {
if (INET_MATCH(sk, acookie, saddr, daddr, ports, dif))
goto hit; /* You sunk my battleship! */
}
The sk_for_each() does use prefetch() hints but only the begining of
"struct sock" is prefetched.
As INET_MATCH first comparison uses inet_sk(__sk)->daddr, wich is far
away from the begining of "struct sock", it has to bring into CPU
cache cold cache line. Each iteration has to use at least 2 cache
lines.
This can be problematic if some chains are very long.
2) The goal
-----------
The idea I had is to change things so that INET_MATCH() may return
FALSE in 99% of cases only using the data already in the CPU cache,
using one cache line per iteration.
3) Description of the patch
---------------------------
Adds a new 'unsigned int skc_hash' field in 'struct sock_common',
filling a 32 bits hole on 64 bits platform.
struct sock_common {
unsigned short skc_family;
volatile unsigned char skc_state;
unsigned char skc_reuse;
int skc_bound_dev_if;
struct hlist_node skc_node;
struct hlist_node skc_bind_node;
atomic_t skc_refcnt;
+ unsigned int skc_hash;
struct proto *skc_prot;
};
Store in this 32 bits field the full hash, not masked by (ehash_size -
1) Using this full hash as the first comparison done in INET_MATCH
permits us immediatly skip the element without touching a second cache
line in case of a miss.
Suppress the sk_hashent/tw_hashent fields since skc_hash (aliased to
sk_hash and tw_hash) already contains the slot number if we mask with
(ehash_size - 1)
File include/net/inet_hashtables.h
64 bits platforms :
#define INET_MATCH(__sk, __hash, __cookie, __saddr, __daddr, __ports, __dif)\
(((__sk)->sk_hash == (__hash))
((*((__u64 *)&(inet_sk(__sk)->daddr)))== (__cookie)) && \
((*((__u32 *)&(inet_sk(__sk)->dport))) == (__ports)) && \
(!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif))))
32bits platforms:
#define TCP_IPV4_MATCH(__sk, __hash, __cookie, __saddr, __daddr, __ports, __dif)\
(((__sk)->sk_hash == (__hash)) && \
(inet_sk(__sk)->daddr == (__saddr)) && \
(inet_sk(__sk)->rcv_saddr == (__daddr)) && \
(!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif))))
- Adds a prefetch(head->chain.first) in
__inet_lookup_established()/__tcp_v4_check_established() and
__inet6_lookup_established()/__tcp_v6_check_established() and
__dccp_v4_check_established() to bring into cache the first element of the
list, before the {read|write}_lock(&head->lock);
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Acked-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
95 lines
1.9 KiB
C
95 lines
1.9 KiB
C
#ifndef __LINUX_TC_EM_META_H
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#define __LINUX_TC_EM_META_H
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#include <linux/pkt_cls.h>
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enum
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{
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TCA_EM_META_UNSPEC,
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TCA_EM_META_HDR,
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TCA_EM_META_LVALUE,
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TCA_EM_META_RVALUE,
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__TCA_EM_META_MAX
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};
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#define TCA_EM_META_MAX (__TCA_EM_META_MAX - 1)
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struct tcf_meta_val
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{
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__u16 kind;
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__u8 shift;
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__u8 op;
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};
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#define TCF_META_TYPE_MASK (0xf << 12)
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#define TCF_META_TYPE(kind) (((kind) & TCF_META_TYPE_MASK) >> 12)
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#define TCF_META_ID_MASK 0x7ff
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#define TCF_META_ID(kind) ((kind) & TCF_META_ID_MASK)
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enum
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{
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TCF_META_TYPE_VAR,
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TCF_META_TYPE_INT,
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__TCF_META_TYPE_MAX
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};
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#define TCF_META_TYPE_MAX (__TCF_META_TYPE_MAX - 1)
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enum
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{
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TCF_META_ID_VALUE,
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TCF_META_ID_RANDOM,
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TCF_META_ID_LOADAVG_0,
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TCF_META_ID_LOADAVG_1,
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TCF_META_ID_LOADAVG_2,
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TCF_META_ID_DEV,
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TCF_META_ID_PRIORITY,
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TCF_META_ID_PROTOCOL,
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TCF_META_ID_PKTTYPE,
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TCF_META_ID_PKTLEN,
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TCF_META_ID_DATALEN,
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TCF_META_ID_MACLEN,
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TCF_META_ID_NFMARK,
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TCF_META_ID_TCINDEX,
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TCF_META_ID_RTCLASSID,
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TCF_META_ID_RTIIF,
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TCF_META_ID_SK_FAMILY,
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TCF_META_ID_SK_STATE,
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TCF_META_ID_SK_REUSE,
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TCF_META_ID_SK_BOUND_IF,
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TCF_META_ID_SK_REFCNT,
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TCF_META_ID_SK_SHUTDOWN,
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TCF_META_ID_SK_PROTO,
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TCF_META_ID_SK_TYPE,
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TCF_META_ID_SK_RCVBUF,
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TCF_META_ID_SK_RMEM_ALLOC,
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TCF_META_ID_SK_WMEM_ALLOC,
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TCF_META_ID_SK_OMEM_ALLOC,
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TCF_META_ID_SK_WMEM_QUEUED,
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TCF_META_ID_SK_RCV_QLEN,
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TCF_META_ID_SK_SND_QLEN,
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TCF_META_ID_SK_ERR_QLEN,
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TCF_META_ID_SK_FORWARD_ALLOCS,
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TCF_META_ID_SK_SNDBUF,
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TCF_META_ID_SK_ALLOCS,
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TCF_META_ID_SK_ROUTE_CAPS,
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TCF_META_ID_SK_HASH,
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TCF_META_ID_SK_LINGERTIME,
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TCF_META_ID_SK_ACK_BACKLOG,
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TCF_META_ID_SK_MAX_ACK_BACKLOG,
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TCF_META_ID_SK_PRIO,
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TCF_META_ID_SK_RCVLOWAT,
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TCF_META_ID_SK_RCVTIMEO,
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TCF_META_ID_SK_SNDTIMEO,
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TCF_META_ID_SK_SENDMSG_OFF,
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TCF_META_ID_SK_WRITE_PENDING,
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__TCF_META_ID_MAX
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};
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#define TCF_META_ID_MAX (__TCF_META_ID_MAX - 1)
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struct tcf_meta_hdr
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{
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struct tcf_meta_val left;
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struct tcf_meta_val right;
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};
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#endif
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