netdev - [PATCH ipsec-next 0/2] xfrm interface: use hash to store xfrmi contexts

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Date:   Thu,  9 Jul 2020 13:16:50 +0300
From:   Eyal Birger <eyal.birger@...il.com>
To:     steffen.klassert@...unet.com, davem@...emloft.net,
        herbert@...dor.apana.org.au, netdev@...r.kernel.org
Cc:     Eyal Birger <eyal.birger@...il.com>
Subject: [PATCH ipsec-next 0/2] xfrm interface: use hash to store xfrmi contexts

When having many xfrm interfaces, the linear lookup of devices based on
if_id becomes costly.

The first patch refactors xfrmi_decode_session() to use the xi used in
the netdevice priv context instead of looking it up in the list based
on ifindex. This is needed in order to use if_id as the only key used
for xi lookup.

The second patch extends the existing infrastructure - which already
stores the xfrmi contexts in an array of lists - to use a hash of the
if_id.

Example benchmarks:
- running on a KVM based VM
- xfrm tunnel mode between two namespaces
- xfrm interface in one namespace (10.0.0.2)

Before this change set:

Single xfrm interface in namespace:
$ netperf -H 10.0.0.2 -l8 -I95,10 -t TCP_STREAM

MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 10.0.0.2 () port 0 AF_INET : +/-5.000% @ 95% conf.  : demo
Recv   Send    Send                          
Socket Socket  Message  Elapsed              
Size   Size    Size     Time     Throughput  
bytes  bytes   bytes    secs.    10^6bits/sec  

131072  16384  16384    8.00      298.36

After adding 400 xfrmi interfaces in the same namespace:

$ netperf -H 10.0.0.2 -l8 -I95,10 -t TCP_STREAM

MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 10.0.0.2 () port 0 AF_INET : +/-5.000% @ 95% conf.  : demo
Recv   Send    Send                          
Socket Socket  Message  Elapsed              
Size   Size    Size     Time     Throughput  
bytes  bytes   bytes    secs.    10^6bits/sec  

131072  16384  16384    8.00      221.77   

After this patchset there was no observed change after adding the
xfrmi interfaces.

Eyal Birger (2):
  xfrm interface: avoid xi lookup in xfrmi_decode_session()
  xfrm interface: store xfrmi contexts in a hash by if_id

 net/xfrm/xfrm_interface.c | 52 +++++++++++++++++++++++++--------------
 1 file changed, 33 insertions(+), 19 deletions(-)

-- 
2.25.1