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| author | Eric Dumazet <eric.dumazet@gmail.com> | 2010-10-20 22:03:38 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2010-10-21 03:09:41 -0700 |
| commit | 9b0c290e78d667e6a483bde8c7cef7dd15f49017 (patch) | |
| tree | ed68f6cbcc9a512106217694b16a846147cdf54a | |
| parent | 7b5edbc4cfe2297b0915adea5aa1eafcafadbf06 (diff) | |
| download | lwn-9b0c290e78d667e6a483bde8c7cef7dd15f49017.tar.gz lwn-9b0c290e78d667e6a483bde8c7cef7dd15f49017.zip | |
fib: introduce fib_alias_accessed() helper
Perf tools session at NFWS 2010 pointed out a false sharing on struct
fib_alias that can be avoided pretty easily, if we set FA_S_ACCESSED bit
only if needed (ie : not already set)
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/ipv4/fib_hash.c | 3 | ||||
| -rw-r--r-- | net/ipv4/fib_lookup.h | 7 | ||||
| -rw-r--r-- | net/ipv4/fib_semantics.c | 2 | ||||
| -rw-r--r-- | net/ipv4/fib_trie.c | 3 |
4 files changed, 12 insertions, 3 deletions
diff --git a/net/ipv4/fib_hash.c b/net/ipv4/fib_hash.c index 4f1aafd3ba89..43e1c594ce8f 100644 --- a/net/ipv4/fib_hash.c +++ b/net/ipv4/fib_hash.c @@ -335,7 +335,8 @@ void fib_table_select_default(struct fib_table *tb, if (!next_fi->fib_nh[0].nh_gw || next_fi->fib_nh[0].nh_scope != RT_SCOPE_LINK) continue; - fa->fa_state |= FA_S_ACCESSED; + + fib_alias_accessed(fa); if (fi == NULL) { if (next_fi != res->fi) diff --git a/net/ipv4/fib_lookup.h b/net/ipv4/fib_lookup.h index 5072d8effd5d..a29edf2219c8 100644 --- a/net/ipv4/fib_lookup.h +++ b/net/ipv4/fib_lookup.h @@ -17,6 +17,13 @@ struct fib_alias { #define FA_S_ACCESSED 0x01 +/* Dont write on fa_state unless needed, to keep it shared on all cpus */ +static inline void fib_alias_accessed(struct fib_alias *fa) +{ + if (!(fa->fa_state & FA_S_ACCESSED)) + fa->fa_state |= FA_S_ACCESSED; +} + /* Exported by fib_semantics.c */ extern int fib_semantic_match(struct list_head *head, const struct flowi *flp, diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c index 6734c9cab248..3e0da3ef6116 100644 --- a/net/ipv4/fib_semantics.c +++ b/net/ipv4/fib_semantics.c @@ -901,7 +901,7 @@ int fib_semantic_match(struct list_head *head, const struct flowi *flp, if (fa->fa_scope < flp->fl4_scope) continue; - fa->fa_state |= FA_S_ACCESSED; + fib_alias_accessed(fa); err = fib_props[fa->fa_type].error; if (err == 0) { diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c index 31494f335686..cd5e13aee7d5 100644 --- a/net/ipv4/fib_trie.c +++ b/net/ipv4/fib_trie.c @@ -1838,7 +1838,8 @@ void fib_table_select_default(struct fib_table *tb, if (!next_fi->fib_nh[0].nh_gw || next_fi->fib_nh[0].nh_scope != RT_SCOPE_LINK) continue; - fa->fa_state |= FA_S_ACCESSED; + + fib_alias_accessed(fa); if (fi == NULL) { if (next_fi != res->fi) |