linux-kernel - [PATCH 0/5] Rhashtable: convert to bit-spin locks.

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Date:   Fri, 06 Jul 2018 17:22:30 +1000
From:   NeilBrown <neilb@...e.com>
To:     Thomas Graf <tgraf@...g.ch>,
        Herbert Xu <herbert@...dor.apana.org.au>
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 0/5] Rhashtable: convert to bit-spin locks.

bit-spinlocks are ideal for locking individual chains of a
hashtable as they do not take extra memory, and they share
a cachle line with the chain head which needs to be loaded (and often
written) anyway.

bit-spinlocks are not fair, but this is only a problem if contention
is likely.  Resizing hashtable are designed to avoid contention on
individual chains - when chains have more than a very few object, the
table is resized.

This is a resend of patches which have been previously posted.  The
only comment raised before concerned the need for lockdep support and
so the last patch was written and posted.
The only changes is that another occurrence of 'locks_mul' needed to
be removed.

Thanks,
NeilBrown

---

NeilBrown (5):
      rhashtable: use cmpxchg() in nested_table_alloc()
      rhashtable: don't hold lock on first table throughout insertion.
      rhashtable: allow rht_bucket_var to return NULL.
      rhashtable: use bit_spin_locks to protect hash bucket.
      rhashtable: add lockdep tracking to bucket bit-spin-locks.

 include/linux/rhashtable-types.h |    2 
 include/linux/rhashtable.h       |  216 +++++++++++++++++++++++++-------------
 ipc/util.c                       |    1 
 lib/rhashtable.c                 |  188 ++++++++++++++++-----------------
 net/bridge/br_fdb.c              |    1 
 net/bridge/br_vlan.c             |    1 
 net/bridge/br_vlan_tunnel.c      |    1 
 net/ipv4/ipmr.c                  |    1 
 net/ipv6/ip6mr.c                 |    1 
 net/netfilter/nf_tables_api.c    |    1 
 10 files changed, 233 insertions(+), 180 deletions(-)

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