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%. As a Xen guest, this profile was gathered using perf(1) and the kernel's software cpu-clock soft interrupts, not the hardware NMI. Other EC2 instance types, such as C5 or M5, use the AWS Nitro Hypervisor.

Speed 52

Speed Java AWS Virtualization 52

All Things Distributed

JANUARY 18, 2012

Amazon DynamoDB offers low, predictable latencies at any scale. Amazon DynamoDB stores data on Solid State Drives (SSDs) and replicates it synchronously across multiple AWS Availability Zones in an AWS Region to provide built-in high availability and data durability. s read latency, particularly as dataset sizes grow.

Scalability 167

Scalability Database Ecommerce Latency 167

The Morning Paper

MAY 28, 2019

We don’t talk about energy as often as we probably should on this blog, but it’s certainly true that our data centres and various IT systems consume an awful lot of it. The goal is to produce a low-energy hardware classifier for embedded applications doing local processing of sensor data. Introducing race logic.

Energy 52

Energy Hardware Efficiency Architecture 52

Brendan Gregg

SEPTEMBER 25, 2021

A Cassandra database cluster had switched to Ubuntu and noticed write latency increased by over 30%. As a Xen guest, this profile was gathered using perf(1) and the kernel's software cpu-clock soft interrupts, not the hardware NMI. Other EC2 instance types, such as C5 or M5, use the AWS Nitro Hypervisor.

Speed 40

Speed Java AWS Virtualization 40

Percona

APRIL 17, 2023

The CFQ works well for many general use cases but lacks latency guarantees. The deadline excels at latency-sensitive use cases ( like databases ), and noop is closer to no schedule at all. By default, most Linux installs use the CFQ ( Completely-Fair Queue ) scheduler. Two other schedulers are deadline and noop.

Best Practices 52

Best Practices Design Tuning Database 52

Adrian Cockcroft

NOVEMBER 11, 2019

This discussion focuses on hardware, software and operational failure modes. Collecting some critical metrics at one second intervals, with a total observability latency of ten seconds or less matches the human attention span much better. This is why most AWS regions have three availability zones.

Latency 52

Latency Engineering Systems Hardware 52

Adrian Cockcroft

NOVEMBER 11, 2019

This discussion focuses on hardware, software and operational failure modes. Collecting some critical metrics at one second intervals, with a total observability latency of ten seconds or less matches the human attention span much better. This is why most AWS regions have three availability zones.

Latency 53

Latency Engineering Systems Hardware 53

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. Just from a quick search, see this presentation PDF , which digs into oops message components. Many new tools can now be written, and the main toolkit we're working on is [bcc].

Virtualization 76

Virtualization AWS Engineering Hardware 76

Smashing Magazine

JANUARY 6, 2020

Estimated Input Latency tells us if we are hitting that threshold, and ideally, it should be below 50ms. Designed for the modern web, it responds to actual congestion, rather than packet loss like TCP does, it is significantly faster , with higher throughput and lower latency — and the algorithm works differently.

Performance 145

Performance Cache Network Metrics 145

Smashing Magazine

JANUARY 7, 2019

Estimated Input Latency tells us if we are hitting that threshold, and ideally, it should be below 50ms. On the other hand, we have hardware constraints on memory and CPU due to JavaScript parsing times (we’ll talk about them in detail later). A good starting point is to choose a good default stack for your application.

Performance 104

Performance Cache Network Metrics 104

Smashing Magazine

JANUARY 11, 2021

Estimated Input Latency tells us if we are hitting that threshold, and ideally, it should be below 50ms. Designed for the modern web, it responds to actual congestion, rather than packet loss like TCP does, it is significantly faster , with higher throughput and lower latency — and the algorithm works differently.

Performance 145

Performance Cache Media Metrics 145