Brendan Gregg

SEPTEMBER 25, 2021

A Cassandra database cluster had switched to Ubuntu and noticed write latency increased by over 30%. As (C) looked like a kernel rebuild, I started with (D) and (E). ## 5. I also rewrote this in C and called gettimeofday(2) directly: $ cat gettimeofdaybench.c. What on Earth is Ubuntu doing that results in 30% higher CPU time!?

Speed 126

Speed Java AWS Virtualization 126

Brendan Gregg

SEPTEMBER 25, 2021

A Cassandra database cluster had switched to Ubuntu and noticed write latency increased by over 30%. As (C) looked like a kernel rebuild, I started with (D) and (E). I also rewrote this in C and called gettimeofday(2) directly: $ cat gettimeofdaybench.c What on Earth is Ubuntu doing that results in 30% higher CPU time!?

Speed 52

Speed Java AWS Virtualization 52

Brendan Gregg

SEPTEMBER 25, 2021

A Cassandra database cluster had switched to Ubuntu and noticed write latency increased by over 30%. As (C) looked like a kernel rebuild, I started with (D) and (E). ## 6. I also rewrote this in C and called gettimeofday(2) directly: $ cat gettimeofdaybench.c What on Earth is Ubuntu doing that results in 30% higher CPU time!?

Speed 40

Speed Java AWS Virtualization 40

Brendan Gregg

MAY 8, 2021

An average of 434 ms is awful, and a small queue size (aqu-sz) indicates it's a problem with the disk and not the workload applied. Update: Some modern drives after 2015 are sealed with [helium].) Rotational disks have extra latency from head seeks for random I/O, and spin ups from the idle state. Hit Ctrl-C to end.

Performance 40

Performance Latency Speed Systems 40

The Netflix TechBlog

AUGUST 29, 2023

A brief history of IPC at Netflix Netflix was early to the cloud, particularly for large-scale companies: we began the migration in 2008, and by 2010, Netflix streaming was fully run on AWS. In 2010, however, nearly none of it existed: the CNCF wasn’t formed until 2015!

Traffic 220

Traffic Latency Cloud C++ 220

Smashing Magazine

JANUARY 7, 2019

Estimated Input Latency tells us if we are hitting that threshold, and ideally, it should be below 50ms. In real-life world, most products aren’t even close: an average bundle size today is around 400KB , which is up 35% compared to late 2015. On a middle-class mobile device, that accounts for 30-35 seconds for Time-To-Interactive.

Performance 103

Performance Cache Metrics Network 103

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