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. Was there some other program consuming CPU, like a misbehaving Ubuntu service that wasn't in CentOS? These can be invisible to top(8).

Speed 126

Speed Java AWS Virtualization 126

The Morning Paper

DECEMBER 10, 2019

This is a companion paper to the " persistent problem " piece that we looked at earlier this week, going a little deeper into the object pointer representation choices and the mapping of a virtual object space into physical address spaces. " Epheremal virtual addresses don’t cut it as the basis for persistent pointers.

Hardware 52

Hardware Virtualization Operating System Programming 52

Brendan Gregg

AUGUST 18, 2019

For example, iostat(1), or a monitoring agent, may tell you your average disk latency, but not the distribution of this latency. For smaller environments, it can be of more use helping eliminate latency outliers. bpftrace uses BPF (Berkeley Packet Filter), an in-kernel execution engine that processes a virtual instruction set.

Latency 68

Latency C++ Cache Programming 68

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. It was a great privilege. That's about 24 hours from now!

Performance 52

Performance Latency Cache Virtualization 52

Enprowess

SEPTEMBER 7, 2021

JavaScript is one of the most famous and loved programming languages nowadays. It is growing day by day and has kept its position for eight years in a row and belongs to the top ten most loved programming languages. with its low latency I/O operations, gives the benefit of ‘No buffering’ to developers. Faster virtual DOM.

Open Source 52

Open Source Virtualization Programming Servers 52

Brendan Gregg

OCTOBER 8, 2018

more capable, and built from the ground up for the modern era of the eBPF virtual machine. Screenshot: tracing read latency for PID 181: # bpftrace -e 'kprobe:vfs_read /pid == 30153/ { @start[tid] = nsecs; } kretprobe:vfs_read /@start[tid]/ { @ns = hist(nsecs - @start[tid]); delete(@start[tid]); }'. ^C

C++ 110

C++ Virtualization Programming Latency 110

ScaleOut Software

JULY 14, 2021

The Microsoft Azure IoT ecosystem offers a rich set of capabilities for processing IoT telemetry, from its arrival in the cloud through its storage in databases and data lakes. Acting as a switchboard for incoming and outgoing messages, Azure IoT Hub forms the core of these capabilities.

IoT 52

IoT Azure Analytics Serverless 52

Dotcom-Montior

NOVEMBER 24, 2021

With the rapid advancements in web application technologies, programming languages, cloud computing services, microservices, hybrid environments, etc., This complexity is “hidden” to the end user, like how an API (Application Programming Interface) operates, whether that is an actual user or another computer. No Shared Memory.

Systems 74

Systems Monitoring Hardware Network 74

The Morning Paper

JUNE 30, 2019

In such a situation I’d expect to see unusually high latencies, but normal throughput). I was only partially right (there is a steady-state queue involved)… Plus, although it’s not described, the performance degradation observed in this case would almost certainly be poor latency and poor throughput.

Traffic 75

Traffic Latency Programming Scalability 75

ScaleOut Software

JULY 19, 2021

As shown in the following diagram, a typical analytics system receives messages from a message hub, such as Kafka, which buffers incoming messages from the data sources until they can be processed. The complex web of communicating devices that surrounds us needs intelligent, real-time device tracking to extract its full benefits.

IoT 78

IoT Analytics Big Data Architecture 78

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. Was there some other program consuming CPU, like a misbehaving Ubuntu service that wasn't in CentOS? These can be invisible to top(8).

Speed 52

Speed Java AWS Virtualization 52

The Morning Paper

DECEMBER 8, 2019

On the last morning of the conference Daniel Bittman presented some of the work being done in the context of the Twizzler OS project to explore new programming models for NVM. The starting point is a set of three asumptions for an NVM-based programming model: Compared to traditional persistent media, NVM is fast.

Hardware 56

Hardware Programming Media Storage 56

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. Was there some other program consuming CPU, like a misbehaving Ubuntu service that wasn't in CentOS? These can be invisible to top(8).

Speed 40

Speed Java AWS Virtualization 40

VoltDB

JULY 10, 2018

This goal has been attempted to be addressed from the beginning of time: think of Object Oriented Programming, Service Oriented Architecture, Enterprise Service Bus and now Microservices. In these use cases, data processing usually has less than a 5 milliseconds latency budget. Real-World Example Problem.

Architecture 40

Architecture Scalability Ecommerce Latency 40

VoltDB

JULY 10, 2018

This goal has been attempted to be addressed from the beginning of time: think of Object Oriented Programming, Service Oriented Architecture, Enterprise Service Bus and now Microservices. In these use cases, data processing usually has less than a 5 milliseconds latency budget. Real-World Example Problem.

Architecture 40

Architecture Scalability Ecommerce Latency 40

Brendan Gregg

JANUARY 17, 2018

OSes usually show you virtual memory and resident memory, shown as the "VIRT" and "RES" columns in top. For large processes (>100 Gbytes), the delays in setting and reading pagemap data can be large, so I've added the Est(s) column to better reflect the real span of the WSS measurement. ### How it works My wss.pl

Cache 71

Cache Latency C++ Programming 71

Brendan Gregg

AUGUST 8, 2017

This measures demand, which can be greater than what the system is currently processing. 42/3411 43603. . ## History The original load averages show only CPU demand: the number of processes running plus those waiting to run. The load average is an average of the number of runnable processes over a given time period.

Latency 111

Latency Metrics C++ Systems 111

O'Reilly Software

MARCH 7, 2018

Software today is not typically a single program—something that is executed by an operator or user, producing a result to that person—but rather a service : something that runs for the benefit of its consumers, a provider of value. The most common programming task in the world. Let’s dive into this concept for a bit.

Transportation 72

Transportation Java Programming Architecture 72

All Things Distributed

AUGUST 16, 2011

There are different considerations when deciding where to allocate resources with latency and cost being the two obvious ones, but compliance sometimes plays an important role as well. The Cloud First strategy is most visible with new Federal IT programs, which are all designed to be â??Cloud Cloud Readyâ??; Government and Big Data.

AWS 111

AWS Government Big Data Cloud 111

Brendan Gregg

OCTOBER 7, 2018

more capable, and built from the ground up for the modern era of the eBPF virtual machine. Screenshot: tracing read latency for PID 181: # bpftrace -e 'kprobe:vfs_read /pid == 30153/ { @start[tid] = nsecs; } kretprobe:vfs_read /@start[tid]/ { @ns = hist(nsecs - @start[tid]); delete(@start[tid]); }'. ^C

C++ 40

C++ Virtualization Programming Latency 40

Brendan Gregg

JANUARY 16, 2018

OSes usually show you virtual memory and resident memory, shown as the "VIRT" and "RES" columns in top. For large processes (>100 Gbytes), the delays in setting and reading pagemap data can be large, so I've added the Est(s) column to better reflect the real span of the WSS measurement. ### How it works My wss.pl

Cache 40

Cache Latency C++ Programming 40

Alex Russell

APRIL 29, 2021

Now in development in WebKit after years of radio silence, WebXR APIs provide Augmented Reality and Virtual Reality input and scene information to web applications. Provides support for "unread counts", e.g. for email and chat programs. Helps media apps on the web save battery when doing video processing.

Media 145

Media Games Education Engineering 145

SQL Server According to Bob

JANUARY 11, 2020

DBCC Page Auditing DBCC page auditing is the process of executing common DBCC consistency checks as pages are read from disk. ​​ Obtain assistance from your I/O vendor ​​ if you ​​ encounter retries.

Servers 40

Servers Cache Database Media 40

SQL Server According to Bob

JANUARY 11, 2020

Many high-end disk subsystems provide high-speed cache facilities to reduce the latency of read and write operations. Because the log record for a page modification does not ​​ exist, the recovery process cannot determine the proper transactional state of the page. Latch page 150 to prevent further modifications.

Servers 40

Servers Cache Media Hardware 40