diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2023-03-23 21:55:32 +0100 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2023-03-28 18:52:28 -0700 |
| commit | bc9d3a9f2afca189a6ae40225b6985e3c775375e (patch) | |
| tree | 4e23464338077861625422ed7db14381cc888997 /net/core/rtnetlink.c | |
| parent | d288a162dd1c73507da582966f17dd226e34a0c0 (diff) | |
net: dst: Switch to rcuref_t reference counting
Under high contention dst_entry::__refcnt becomes a significant bottleneck.
atomic_inc_not_zero() is implemented with a cmpxchg() loop, which goes into
high retry rates on contention.
Switch the reference count to rcuref_t which results in a significant
performance gain. Rename the reference count member to __rcuref to reflect
the change.
The gain depends on the micro-architecture and the number of concurrent
operations and has been measured in the range of +25% to +130% with a
localhost memtier/memcached benchmark which amplifies the problem
massively.
Running the memtier/memcached benchmark over a real (1Gb) network
connection the conversion on top of the false sharing fix for struct
dst_entry::__refcnt results in a total gain in the 2%-5% range over the
upstream baseline.
Reported-by: Wangyang Guo <wangyang.guo@intel.com>
Reported-by: Arjan Van De Ven <arjan.van.de.ven@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20230307125538.989175656@linutronix.de
Link: https://lore.kernel.org/r/20230323102800.215027837@linutronix.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/core/rtnetlink.c')
| -rw-r--r-- | net/core/rtnetlink.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index b7b1661d0d56..906aebdc566b 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -843,7 +843,7 @@ int rtnl_put_cacheinfo(struct sk_buff *skb, struct dst_entry *dst, u32 id, if (dst) { ci.rta_lastuse = jiffies_delta_to_clock_t(jiffies - dst->lastuse); ci.rta_used = dst->__use; - ci.rta_clntref = atomic_read(&dst->__refcnt); + ci.rta_clntref = rcuref_read(&dst->__rcuref); } if (expires) { unsigned long clock; |