PEX 8696, PCI Express Gen 2 Switch, 96 Lanes, 24 Ports
performancePAK
TM
Exclusive to PLX,
performancePAK
is a suite of unique
and innovative performance features which allows
PLX’s Gen 2 switches to be the highest performing Gen
2 switches in the market today. The
performancePAK
features consists of the Read Pacing, Multicast, and
Dynamic Buffer Pool.
Read Pacing
The Read Pacing feature allows users to throttle the
amount of read requests being made by downstream
devices. When a downstream device requests several
long reads back-to-back, the Root Complex gets tied up
in serving that downstream port. If that port has a narrow
link and is therefore slow in receiving these read packets
from the Root Complex, then other downstream ports
may become starved – thus, impacting performance. The
Read Pacing feature enhances performances by allowing
for the adequate servicing of all downstream devices.
Multicast
The Multicast feature enables the copying of data
(packets) from one ingress port to multiple (up to 23)
egress ports in one transaction allowing for higher
performance in dual-graphics, storage, security, and
redundant applications, among others. Multicast relieves
the CPU from having to conduct multiple redundant
transactions, resulting in higher system performance.
Dynamic Buffer Pool
The PEX 8696 employs a dynamic buffer pool for Flow
Control (FC) management. As opposed to a static buffer
scheme which assigns fixed, static buffers to each port,
PLX’s dynamic buffer allocation scheme utilizes a
common pool of FC Credits which are shared by other
ports. This shared buffer pool is fully programmable by
the user, so FC credits can be allocated among the ports
as needed. Not only does this prevent wasted buffers and
inappropriate buffer assignments, any unallocated
buffers remain in the common buffer pool and can then
be used for faster FC credit updates.
Performance Monitoring
The PEX 8696’s real time performance monitoring
allows users to literally “see” ingress and egress
performance on each port as traffic passes through the
switch using PLX’s Software Development Kit (SDK).
The monitoring is completely passive and therefore has
no affect on overall system performance. Internal
counters provide extensive granularity down to traffic &
packet type and even allows for the filtering of traffic
(i.e. count only Memory Writes).
SerDes Eye Capture
Users can evaluate their system’s signal integrity at the
physical layer using the PEX 8696’s SerDes Eye
Capture feature. Using PLX’s SDK, users can view the
receiver eye of any lane on the switch. Users can then
modify SerDes settings and see the impact on the
receiver eye. Figure 5 shows a screenshot of the SerDes
Eye Capture feature in the SDK.
Figure 5. SerDes Eye Capture
Error Injection & SerDes Loopback
Using the PEX 8696’s Error Injection feature, users can
inject malformed packets and/or fatal errors into their
system and evaluate a system’s ability to detect and
recover from such errors. The PEX 8696 also supports
Internal Tx, External Tx, Recovered Clock, and
Recovered Data Loopback modes.
Applications
Suitable for
host-centric
as well as
peer-to-peer traffic
patterns,
the PEX 8696 can be configured for a wide
variety of form factors and applications.
Host Centric Fan-out
The PEX 8696, with its symmetric or asymmetric lane
configuration capability, allows user-specific tuning to a
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visionPAK
TM
Another PLX exclusive,
visionPAK
is a debug
diagnostics suite of integrated hardware and software
instruments that users can use to help bring their systems
to market faster.
visionPAK
features consist of
Performance Monitoring, SerDes Eye Capture, Error
Injection, SerDes Loopback, and more.
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PLX [ PLX TECHNOLOGY ]
