Brendan Gregg

SEPTEMBER 25, 2021

A Cassandra database cluster had switched to Ubuntu and noticed write latency increased by over 30%. Was there some other program consuming CPU, like a misbehaving Ubuntu service that wasn't in CentOS? As (C) looked like a kernel rebuild, I started with (D) and (E). But I'm not completely sure. Ubuntu is 5x slower.

Speed 52

Speed Java AWS Virtualization 52

Brendan Gregg

AUGUST 8, 2017

TABLE OF EXP(-T/C) FOR T = 5 SEC. EXPFF: EXP 0.920043902 ;C = 1 MIN EXP 0.983471344 ;C = 5 MIN EXP 0.994459811 ;C = 15 MIN. 90491 N|rnberg (Germany) Consulting+Networking+Programming+etc'ing 42. Latency was acceptable and no one complained. kernel/sched.c.orig Fri Oct 29 10:31:11 1993 kernel/sched.c

Latency 111

Latency Metrics C++ Systems 111

Brendan Gregg

SEPTEMBER 25, 2021

A Cassandra database cluster had switched to Ubuntu and noticed write latency increased by over 30%. Was there some other program consuming CPU, like a misbehaving Ubuntu service that wasn't in CentOS? As a Xen guest, this profile was gathered using perf(1) and the kernel's software cpu-clock soft interrupts, not the hardware NMI.

Speed 40

Speed Java AWS Virtualization 40

John McCalpin

NOVEMBER 5, 2016

In the latest (October 2016) revision of Intel’s Instruction Extensions Programming Reference , Intel has disclosed a fairly dramatic departure from these “traditional” approaches. Notes on notation: C[i][j] is invariant in the innermost loop, so I refer to the values in the accumulator as elements of the C array.

Cache 40

Cache C++ Latency Hardware 40

John McCalpin

JANUARY 22, 2018

Each of the two vector units can issue one FMA instruction per cycle, assuming that there are enough independent accumulators to tolerate the 6-cycle dependent-operation latency. This is an uninspiring fraction of peak performance that would normally suggest significant inefficiencies in either the hardware or software.

Latency 40

Latency Hardware Code Testing 40

Alex Russell

JUNE 20, 2020

3] Oh, and it should be imperatively programmed with Lisp-in-C's-clothing. Recall that browsers arose atop platforms that universally provided a host of services by the late 90's: system fonts (to support layout programs, including WYSIWYG editing). multi-tasking & concurrent programming. high-color image raster.

Hardware 55

Hardware Games Java Media 55

The Morning Paper

SEPTEMBER 12, 2019

SQL provides a declarative programming interface, below which the system itself can figure out the most effective execution plans based on data size and statistics, layout, compute hardware etc. The implementations require both SQL and also some UDFs written in C++. Be careful what you ask for (materialize).

Network 44

Network Database Programming Hardware 44

SQL Server According to Bob

JANUARY 11, 2020

Character POS ASCII Value Formula Value A 1 65 67 C 2 67 69 Checksum 136 Comparing ​​ the checksum values indicates ​​ that the values do not match and ​​ damage ​​ has occurred to the data. ​​ Remote mirroring captures writes and duplicates them ​​ remotely.

Servers 40

Servers Cache Database Media 40

All Things Distributed

NOVEMBER 15, 2010

We believe that making these GPU resources available for everyone to use at low cost will drive new innovation in the application of highly parallel programming models. For example, the most fundamental abstraction trade-off has always been latency versus throughput. General Purpose GPU programming. From CPU to GPU.

AWS 136

AWS Latency Programming Architecture 136