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What: /sys/bus/platform/devices/<bpmp-device>/mbwt/<bandwidth-group>/<traffic-type>/bandwidth
Date: September 2026
KernelVersion: 7.4
Contact: Aniruddha TVS Rao <anrao@nvidia.com>
Description:
Provides access to Memory Bandwidth Throttler (MBWT)
controls exposed by BPMP firmware for PCIe traffic and GPU
traffic connected over the chip-to-chip link (NVCLINK) on
the path to DRAM.
The attributes are present only when BPMP firmware reports
support for the MBWT GET_BW and SET_BW requests through the
MBWT query ABI.
Each <bandwidth-group> directory identifies one PCIe bandwidth
group. The available groups and their directory names are
platform-specific. Current platforms use pcie0 through pcie5.
Each bandwidth group has a single shared cap for all traffic
in that group. A group may contain only PCIe devices, only a
GPU connected over NVCLINK, or both PCIe and GPU traffic in a
bifurcated topology.
The <traffic-type> directory selects the traffic type for the
selected group. The following traffic types may be available:
pcie_read
PCIe read traffic
pcie_write
PCIe write traffic
nvclink
GPU traffic connected over NVCLINK
Reading a bandwidth attribute returns the bandwidth cap in GB/s
reported by firmware for that bandwidth group and traffic
type.
Writing an integer to a bandwidth attribute programs the target
bandwidth cap in GB/s for that bandwidth group and traffic
type.
Examples:
cat .../mbwt/pcie0/pcie_write/bandwidth
echo 100 > .../mbwt/pcie0/pcie_write/bandwidth
Users: Platform integration and bandwidth tuning on systems with BPMP
firmware MBWT support.
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