Stephen Hemminger a écrit :
Make FIB TRIE go through sparse checker without warnings.
Signed-off-by: Stephen Hemminger <[EMAIL PROTECTED]>
Hi Stephen
While reviewing your patches (and fib code) I had some questions :
1) I was wondering isn't trie_collect_stats() a potential cpu hog
(big latency) ?
2) struct tnode layout
If tnode->bits is large enough, we allocate a big area
of memory but roughly use only first half of it.
We could use a better scheme with an extra indirection. For small
nodes, we use space right after tnode, but for big nodes, we allocate
a power of two set of pages, to exactly match the memory need.
3) 'pos' and 'bits' fields of 'struct tnode' might be converted to
plain uchar, instead of 5-bits fields, to reduce complexity for
generated code.
4) full_children & empty_children being 'unsigned short',
we probably are limited to 2^15 elements, but I could not
find this limit enforced somewhere.
[FIB]: Reduce text size of net/ipv4/fib_trie.o
In struct tnode, we use two fields of 5 bits for 'pos' and 'bits'.
Switching to plain 'unsigned char' (8 bits) take the same space
because of compiler alignments, and reduce text size by 435 bytes
on i386.
On i386 :
$ size net/ipv4/fib_trie.o.before_patch net/ipv4/fib_trie.o
text data bss dec hex filename
13714 4 64 13782 35d6 net/ipv4/fib_trie.o.before
13279 4 64 13347 3423 net/ipv4/fib_trie.o
Signed-off-by: Eric Dumazet <[EMAIL PROTECTED]>
diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index 2832610..4e91532 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -119,8 +119,8 @@ struct leaf_info {
struct tnode {
t_key key;
unsigned long parent;
- unsigned short pos:5; /* 2log(KEYLENGTH) bits needed */
- unsigned short bits:5; /* 2log(KEYLENGTH) bits needed */
+ unsigned char pos; /* 2log(KEYLENGTH) bits needed */
+ unsigned char bits; /* 2log(KEYLENGTH) bits needed */
unsigned short full_children; /* KEYLENGTH bits needed */
unsigned short empty_children; /* KEYLENGTH bits needed */
struct rcu_head rcu;
