Re: [PATCH net-next v4 0/4] ila: Optimization to preserve value of early demux

2015-12-14 Thread David Miller 
From: Tom Herbert 
Date: Thu, 10 Dec 2015 16:19:29 -0800

> In the current implementation of ILA, LWT is used to perform
> translation on both the input and output paths. This is functional,
> however there is a big performance hit in the receive path. Early
> demux occurs before the routing lookup (a hit actually obviates the
> route lookup). Therefore the stack currently performs early
> demux before translation so that a local connection with ILA
> addresses is never matched. Note that this issue is not just
> with ILA, but pretty much any translated or encapsulated packet
> handled by LWT would miss the opportunity for early demux. Solving
> the general problem seems non trivial since we would need to move
> the route lookup before early demx thereby mitigating the value.
> 
> This patch set addresses the issue for ILA by adding a fast locator
> lookup that occurs before early demux. This done by hooking in to
> NF_INET_PRE_ROUTING
> 
> For the backend we implement an rhashtable that contains identifier
> to locator to mappings. The table also allows more specific matches
> that include original locator and interface.
 ...

Please address Florian's feedback wrt. which nf hook registry interface
should be used, and otherwise I think this series is ready to go.
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[PATCH net-next v4 0/4] ila: Optimization to preserve value of early demux

2015-12-10 Thread Tom Herbert 
In the current implementation of ILA, LWT is used to perform
translation on both the input and output paths. This is functional,
however there is a big performance hit in the receive path. Early
demux occurs before the routing lookup (a hit actually obviates the
route lookup). Therefore the stack currently performs early
demux before translation so that a local connection with ILA
addresses is never matched. Note that this issue is not just
with ILA, but pretty much any translated or encapsulated packet
handled by LWT would miss the opportunity for early demux. Solving
the general problem seems non trivial since we would need to move
the route lookup before early demx thereby mitigating the value.

This patch set addresses the issue for ILA by adding a fast locator
lookup that occurs before early demux. This done by hooking in to
NF_INET_PRE_ROUTING

For the backend we implement an rhashtable that contains identifier
to locator to mappings. The table also allows more specific matches
that include original locator and interface.

This patch set:
 - Add an rhashtable function to atomically replace and element.
   This is useful to implement sub-trees from a table entry
   without needing to use a special anchor structure as the
   table entry.
 - Add a start callback for starting a netlink dump.
 - Creates an ila directory under net/ipv6 and moves ila.c to it.
   ila.c is split into ila_common.c and ila_lwt.c.
 - Implement a table to do identifier->locator mapping. This is
   an rhashtable (in ila_xlat.c).
 - Configuration for the table with netlink.
 - Add a hook into NF_INET_PRE_ROUTING to perform ILA translation
   before early demux.

Changes in v2:
 - Use iptables targets instead of a new xfrm function

Changes in v3:
 - Add __rcu to next pointer in struct ila_map

Changes in v4:
 - Use hook for NF_INET_PRE_ROUTING

Testing:
   Running 200 netperf TCP_RR streams

No ILA, baseline
   79.26% CPU utilization
   1678282 tps
   104/189/390 50/90/99% latencies

ILA before fix (LWT on both input and output)
   81.91% CPU utilization
   1464723 tps (-14.5% from baseline)
   121/215/411 50/90/99% latencies

ILA after fix
   80.62% CPU utilization
   1622985 (-3.4% from baseline)
   110/191/347 50/90/99% latencies


Tom Herbert (4):
  ila: Create net/ipv6/ila directory
  rhashtable: add function to replace an element
  netlink: add a start callback for starting a netlink dump
  ila: Add generic ILA translation facility

 include/linux/netlink.h|   2 +
 include/linux/rhashtable.h |  82 ++
 include/net/genetlink.h|   2 +
 include/net/ila.h  |  18 ++
 include/uapi/linux/ila.h   |  22 ++
 net/ipv6/Makefile  |   2 +-
 net/ipv6/ila.c | 229 ---
 net/ipv6/ila/Makefile  |   7 +
 net/ipv6/ila/ila.h |  48 
 net/ipv6/ila/ila_common.c  | 103 +++
 net/ipv6/ila/ila_lwt.c | 152 ++
 net/ipv6/ila/ila_xlat.c| 679 +
 net/netlink/af_netlink.c   |   4 +
 net/netlink/genetlink.c|  16 ++
 14 files changed, 1136 insertions(+), 230 deletions(-)
 create mode 100644 include/net/ila.h
 delete mode 100644 net/ipv6/ila.c
 create mode 100644 net/ipv6/ila/Makefile
 create mode 100644 net/ipv6/ila/ila.h
 create mode 100644 net/ipv6/ila/ila_common.c
 create mode 100644 net/ipv6/ila/ila_lwt.c
 create mode 100644 net/ipv6/ila/ila_xlat.c

-- 
2.4.6

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