The Netflix TechBlog

AUGUST 29, 2023

In 2010, however, nearly none of it existed: the CNCF wasn’t formed until 2015! If service A needs to talk to clusters B and C, then you need to define clusters B and C as part of A’s proxy config. There is a downside to fetching this data on-demand: this adds latency to the first request to a cluster.

Traffic 229

Traffic Latency Cloud C++ 229

Brendan Gregg

JULY 2, 2021

biolatency Disk I/O latency histogram heat map. runqlat CPU scheduler latency heat map. Then, having discovered everything is C or Python, some rewrite it all in a different language. execsnoop New processes (via exec(2)) table. opensnoop Files opened table. ext4slower Slow filesystem I/O table. BPF up and running!

Latency 144

Latency Cache Energy Systems 144

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 103

Speed Java AWS Virtualization 103

Smashing Magazine

AUGUST 9, 2021

You’ve probably heard things like: “HTTP/3 is much faster than HTTP/2 when there is packet loss”, or “HTTP/3 connections have less latency and take less time to set up”, and probably “HTTP/3 can send data more quickly and can send more resources in parallel”. For example, if we have files A, B, and C, we would have three TCP connections.

Transportation 145

Transportation Internet Internet Network 145

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

Update: Some modern drives after 2015 are sealed with [helium].) From these outputs I try to determine if the problem is: - **The workload**: High-latency disk I/O is commonly caused by the workload applied. 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