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rhashtable: reorganize struct rhashtable layout

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While under frags DDOS I noticed unfortunate false sharing between
@nelems and @params.automatic_shrinking

Move @nelems at the end of struct rhashtable so that first cache line
is shared between all cpus, because almost never dirtied.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit e5d672a0780d9e7118caad4c171ec88b8299398d)
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Eric Dumazet 2018-10-10 12:30:03 -07:00 • committed by Greg Kroah-Hartman
parent cbc45497b3
commit 6060bcdcff
1 changed files with 2 additions and 2 deletions
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4
include/linux/rhashtable.h
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@ -138,7 +138,6 @@ struct rhashtable_params {
/**
* struct rhashtable - Hash table handle
* @tbl: Bucket table
* @nelems: Number of elements in table
* @key_len: Key length for hashfn
* @elasticity: Maximum chain length before rehash
* @p: Configuration parameters
@ -146,10 +145,10 @@ struct rhashtable_params {
* @run_work: Deferred worker to expand/shrink asynchronously
* @mutex: Mutex to protect current/future table swapping
* @lock: Spin lock to protect walker list
* @nelems: Number of elements in table
*/
struct rhashtable {
struct bucket_table __rcu *tbl;
atomic_t nelems;
unsigned int key_len;
unsigned int elasticity;
struct rhashtable_params p;
@ -157,6 +156,7 @@ struct rhashtable {
struct work_struct run_work;
struct mutex mutex;
spinlock_t lock;
atomic_t nelems;
};
/**