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OpenCloudOS-Kernel/include/net/netns/hash.h

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netns: introduce the net_hash_mix "salt" for hashes There are many possible ways to add this "salt", thus I made this patch to be the last in the series to change it if required. Currently I propose to use the struct net pointer itself as this salt, but since this pointer is most often cache-line aligned, shift this right to eliminate the bits, that are most often zeroed. After this, simply add this mix to prepared hashfn-s. For CONFIG_NET_NS=n case this salt is 0 and no changes in hashfn appear. Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-06-17 08:14:11 +08:00
#ifndef __NET_NS_HASH_H__
#define __NET_NS_HASH_H__
#include <asm/cache.h>
struct net;
netns: constify net_hash_mix() and various callers const qualifiers ease code review by making clear which objects are not written in a function. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-19 05:05:33 +08:00
static inline u32 net_hash_mix(const struct net *net)
netns: introduce the net_hash_mix "salt" for hashes There are many possible ways to add this "salt", thus I made this patch to be the last in the series to change it if required. Currently I propose to use the struct net pointer itself as this salt, but since this pointer is most often cache-line aligned, shift this right to eliminate the bits, that are most often zeroed. After this, simply add this mix to prepared hashfn-s. For CONFIG_NET_NS=n case this salt is 0 and no changes in hashfn appear. Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-06-17 08:14:11 +08:00
{
#ifdef CONFIG_NET_NS
/*
* shift this right to eliminate bits, that are
* always zeroed
*/
netns: constify net_hash_mix() and various callers const qualifiers ease code review by making clear which objects are not written in a function. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-19 05:05:33 +08:00
return (u32)(((unsigned long)net) >> L1_CACHE_SHIFT);
netns: introduce the net_hash_mix "salt" for hashes There are many possible ways to add this "salt", thus I made this patch to be the last in the series to change it if required. Currently I propose to use the struct net pointer itself as this salt, but since this pointer is most often cache-line aligned, shift this right to eliminate the bits, that are most often zeroed. After this, simply add this mix to prepared hashfn-s. For CONFIG_NET_NS=n case this salt is 0 and no changes in hashfn appear. Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-06-17 08:14:11 +08:00
#else
return 0;
#endif
}
#endif