inliniac/suricata — pull request #464 by ken-tilera (2013-07-26 08:01:38+00:00)
Title: Add TILE-Gx mPIPE packet processing support.

The TILE-Gx processor includes a packet processing engine, called
mPIPE, that can deliver packets directly into user space memory. It
handles buffer allocation and load balancing (either static 5-tuple
hashing, or dynamic flow affinity hashing are used here). The new
packet source code is in source-mpipe.c and source-mpipe.h

A new Tile runmode is added that configures the Suricata pipelines in
worker mode, where each thread does the entire packet processing
pipeline. It scales across all the Gx chips sizes of 9, 16, 36 or 72
cores. The new runmode is in runmode-tile.c and runmode-tile.h

The configure script detects the TILE-Gx architecture and defines
HAVE_MPIPE, which is then used to conditionally enable the code to
support mPIPE packet processing. Suricata runs on TILE-Gx even without
mPIPE support enabled.

The Suricata Packet structures are allocated by the mPIPE hardware by
allocating the Suricata Packet structure immediatley before the mPIPE
packet buffer and then pushing the mPIPE packet buffer pointer onto
the mPIPE buffer stack. This way, mPIPE writes the packet data into
the buffer, returns the mPIPE packet buffer pointer, which is then
converted into a Suricata Packet pointer for processing inside
Suricata. When the Packet is freed, the buffer is returned to mPIPE's
buffer stack, by setting ReleasePacket to an mPIPE release specific
function.

The code checks for the largest Huge page available in Linux when
Suricata is started. TILE-Gx supports Huge pages sizes of 16MB, 64MB,
256MB, 1GB and 4GB. Suricata then divides one of those page into
packet buffers for mPIPE.

The code is not yet optimized for high performance. Performance
improvements will follow shortly.

The code was originally written by Tom Decanio and then further
modified by Tilera.

This code has been tested with Tilera's Multicore Developement
Environment (MDE) version 4.1.5. The TILEncore-Gx36 (PCIe card) and
TILEmpower-Gx (1U Rack mount).