Messages in this thread Patch in this message | | | Date | Tue, 27 Oct 2009 15:04:36 -0700 | From | Stephen Hemminger <> | Subject | [PATCH] net: fold network name hash (v2) |
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The full_name_hash does not produce a value that is evenly distributed over the lower 8 bits. This causes name hash to be unbalanced with large number of names. There is a standard function to fold in upper bits so use that.
This is independent of possible improvements to full_name_hash() in future.
Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
--- a/net/core/dev.c 2009-10-27 14:54:21.922563076 -0700 +++ b/net/core/dev.c 2009-10-27 15:04:16.733813459 -0700 @@ -86,6 +86,7 @@ #include <linux/socket.h> #include <linux/sockios.h> #include <linux/errno.h> +#include <linux/hash.h> #include <linux/interrupt.h> #include <linux/if_ether.h> #include <linux/netdevice.h> @@ -199,7 +200,7 @@ EXPORT_SYMBOL(dev_base_lock); static inline struct hlist_head *dev_name_hash(struct net *net, const char *name) { unsigned hash = full_name_hash(name, strnlen(name, IFNAMSIZ)); - return &net->dev_name_head[hash & ((1 << NETDEV_HASHBITS) - 1)]; + return &net->dev_name_head[hash_long(hash, NETDEV_HASHBITS)]; } static inline struct hlist_head *dev_index_hash(struct net *net, int ifindex)
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