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Linux NUMA Distances Explained
November 3, 2022TL;DR: The memory latency distances between a node and itself is normalized to 10 (1.0x). Every other distance is scaled relative to that 10 base value. For example, the distance between NUMA Node 0 and 1 is 21 (2.1x), meaning...
Using Linux Kernel Memory Tiering
June 10, 2022In this post, I’ll discuss what memory tiering is, why we need it, and how to use the memory tiering feature available in the mainline v5.15 Kernel. What is Memory Tiering? With the advent of various new memory types, some...
How To map VMWare vSphere/ESXi PMem devices from the Host to Guest VM
February 22, 2022In this post, we’ll use VMWare ESXi 7.0u3 to create a Guest VM running Ubuntu 21.10 with two Virtual Persistent Memory (vPMem) devices, then show how we can map the vPMem device in the host (ESXi) to “nmem” devices in...
How To Emulate CXL Devices using KVM and QEMU
January 20, 2022What is CXL? Compute Express Link (CXL) is an open standard for high-speed central processing unit-to-device and CPU-to-memory connections, designed for high-performance data center computers. CXL is built on the PCI Express physical and electrical interface with protocols in three...
How To Build a custom Linux Kernel to test Data Access Monitor (DAMON)
December 23, 2021DAMON is a data access monitoring framework subsystem for the Linux kernel. DAMON (Data Access MONitor) tool monitors memory access patterns specific to user-space processes introduced in Linux kernel 5.15 LTS, such as operation schemes, physical memory monitoring, and proactive...