4.7.2 QoS class and POCQ resource availability

The POCQ buffers are shared resources for all QoS classes.

The higher the QoS class, the higher the occupancy availability. For example, the HighHigh (HH) QoS class can use all the POCQ entries except for the dedicated snoop filter pool.

The following figure shows the availability of POCQ resources for various QoS levels, using a particular QoS pool that is shared between multiple QoS classes.

Figure 4-1 POCQ availability and QoS classes
To view this graphic, your browser must support the SVG format. Either install a browser with native support, or install an appropriate plugin such as Adobe SVG Viewer.


The QoS pools are:

hh_poolAvailable for HH class.
h_poolAvailable for H class and HH class.
m_poolAvailable for M class, H class, and HH class.
l_poolAvailable for all classes.
seqSnoop filter evictions only.

This scheme enables a higher-priority QoS class to have more POCQ resources for transaction processing, and prevents a lower-priority QoS from using all the POCQ. The level of POCQ availability decreases for the lower QoS classes.

QoS pool distribution of the POCQ is software-configurable using the qos_reservation register.

Non-ConfidentialPDF file icon PDF versionARM 100052_0001_00_en
Copyright © 2014, 2015, 2017 ARM Limited or its affiliates. All rights reserved.