diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2023-03-23 21:55:32 +0100 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2023-03-29 03:52:28 +0200 |
| commit | bc9d3a9f2afca189a6ae40225b6985e3c775375e (patch) | |
| tree | 4e23464338077861625422ed7db14381cc888997 /net/bridge | |
| parent | net: dst: Prevent false sharing vs. dst_entry:: __refcnt (diff) | |
| download | linux-bc9d3a9f2afca189a6ae40225b6985e3c775375e.tar.xz linux-bc9d3a9f2afca189a6ae40225b6985e3c775375e.zip | |
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/bridge')
| -rw-r--r-- | net/bridge/br_nf_core.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/bridge/br_nf_core.c b/net/bridge/br_nf_core.c index 8c69f0c95a8e..98aea5485aae 100644 --- a/net/bridge/br_nf_core.c +++ b/net/bridge/br_nf_core.c @@ -73,7 +73,7 @@ void br_netfilter_rtable_init(struct net_bridge *br) { struct rtable *rt = &br->fake_rtable; - atomic_set(&rt->dst.__refcnt, 1); + rcuref_init(&rt->dst.__rcuref, 1); rt->dst.dev = br->dev; dst_init_metrics(&rt->dst, br_dst_default_metrics, true); rt->dst.flags = DST_NOXFRM | DST_FAKE_RTABLE; |