The Morning Paper

NOVEMBER 8, 2020

Virtual consensus in Delos , Balakrishnan et al. Back in 2017 the engineering team at Facebook had a problem. If you think of this a bit like mapping memory addresses to data in memory, then another parallel comes to mind: the virtual address space. We propose the novel abstraction of a virtual shared log (or VirtualLog).

Virtualization 126

Virtualization Latency Storage Systems 126

Brendan Gregg

FEBRUARY 28, 2023

My personal opinion is that I don't see a widespread need for more capacity given horizontal scaling and servers that can already exceed 1 Tbyte of DRAM; bandwidth is also helpful, but I'd be concerned about the increased latency for adding a hop to more memory. Ford, et al., “TCP

Performance 110

Performance Latency Cache Virtualization 110

Brendan Gregg

JULY 4, 2021

## References I've reproduced the talk references below, so you can click on links: - [Gregg 08] Brendan Gregg, “ZFS L2ARC,” [link] Jul 2008 - [Gregg 10] Brendan Gregg, “Visualizations for Performance Analysis (and More),” [link] 2010 - [Greenberg 11] Marc Greenberg, “DDR4: Double the speed, double the latency? Ford, et al., “TCP

Performance 140

Performance Latency Hardware Storage 140

Brendan Gregg

FEBRUARY 28, 2023

My personal opinion is that I don't see a widespread need for more capacity given horizontal scaling and servers that can already exceed 1 Tbyte of DRAM; bandwidth is also helpful, but I'd be concerned about the increased latency for adding a hop to more memory. Ford, et al., “TCP

Performance 52

Performance Latency Cache Virtualization 52

Brendan Gregg

SEPTEMBER 25, 2021

A Cassandra database cluster had switched to Ubuntu and noticed write latency increased by over 30%. CLI tools The Cassandra systems were EC2 virtual machine (Xen) instances. Note that Ubuntu also has a frame to show entry into vDSO (virtual dynamic shared object).

Speed 126

Speed Java AWS Virtualization 126

SQL Performance

APRIL 8, 2019

Back on December 5, 2017, Microsoft announced that they were using AMD EPYC 7551 processors in their storage-optimized Lv2-Series virtual machines. The key specifications for the Lsv2 series virtual machines are shown in Table 1. They feature low latency, local NVMe storage that can directly leverage the 128 PCIe 3.0

Azure 42

Azure Virtualization Storage Benchmarking 42

Brendan Gregg

SEPTEMBER 5, 2017

Here's some output from my zfsdist tool, in bcc/BPF, which measures ZFS latency as a histogram on Linux: # zfsdist. Tracing ZFS operation latency. What happens if processes really do try to populate all that virtual memory? Many new tools can now be written, and the main toolkit we're working on is [bcc]. Hit Ctrl-C to end. ^C

Virtualization 76

Virtualization AWS Engineering Hardware 76