Facebook open-sources new suite of Linux kernel components and tools An integral part of Facebook’s engineering culture has always been our development work on open source solutions that solve real-world production issues and address key challenges in modern large-scale cloud computing. Today, we are announcing a suite of open source Linux kernel components and related tools that address critical
OSes Talk of tech innovation is bullsh*t. Shut up and get the work done – says Linus Torvalds A top life tip, there, from the Linux kernel chieftain OSLS Linus Torvalds believes the technology industry's celebration of innovation is smug, self-congratulatory, and self-serving. The term of art he used was more blunt: "The innovation the industry talks about so much is bullshit," he said. "Anybody c
JVM Performance Tuning
Last week was JBoss World, and it was exciting to be a part of it. I gave a presentation on performance tuning our Enterprise Application Platform or EAP, and it was packed. In fact, people were sitting on the floor in pretty much all available space. What struck me about the presentation, and much of the discussion I had with individuals afterwards, is that JVM tuning is a big topic. So, I though
Learn why and how to build your AI on your terms with a data platform you control. I’ve published multiple benchmarks comparing different PostgreSQL versions, as for example the performance archaeology talk (evaluating PostgreSQL 7.4 up to 9.4), and all those benchmark assumed fixed environment (hardware, kernel, …). Which is fine in many cases (e.g. when evaluating performance impact of a patch),
A recent blog post posed the question Why do we use the Linux kernel's TCP stack?. It triggered a very interesting discussion on Hacker News. I've also thought about this question while working at CloudFlare. My experience mostly comes from working with thousands of production machines here and I can try to answer the question from that perspective. CC BY 2.0 image by John Vetterli Let's start wit
Need to "calculate" optimum ulimit and fs.file-max values according to my own server needs. Please do not conflict with "how to set those limits in various Linux distros" questions. I am asking: Is there any good guide to explain in detail, parameters used for ulimit? (> 2.6 series kernels) Is there any good guide to show fs.file-max usage metrics? Actually there are some old reference i could fin
The Linux kernel is a free and open-source[16]: 4 Unix-like kernel that is used in many computer systems worldwide. The kernel was created by Linus Torvalds in 1991 and was soon adopted as the kernel for the GNU operating system (OS), which was created to be a free replacement for Unix. Since the late 1990s, it has been included in many operating system distributions, many of which are called Lin
プロセスとマルチタスクの実現 Linuxは、多数のプロセスを同時に動作させる事が出来るマルチタスク環境を実現しています。 psコマンドやtopコマンドを実行しプロセスのリストを取得すると多数のプロセスが実行中である事がわかります。 また、これらのプロセス全てが同時に平行して動作しているように見えます。 これはどのようにして実現されているのでしょうか。 一般的に、１つのプロセッサは同時に複数のプログラムを実行する事が出来ません1。 そこで、マルチタスクをサポートするOSでは複数のプロセスを非常に短い時間ずつ切り替えながら実行する事で、体感上は複数のプロセスが同時に実行されているように見せています(図1)。 このような仕組みを実現する為にどんな機能がカーネルへ実装されているのか順に見ていきましょう。 プロセスの切り替え CPU上で処理中のデータを失う事なく現在のプロセスから別のプロセスに切り替
はじめに 会社で PB 級の Hadoop クラスタを運用していますが、ある日から Datanode の CPU system (Kernel 内での CPU 使用率) が高騰し、Job が遅延するという症状が発現しました。Hadoop で CPU system 高騰というと、 Transparent HugePage 設定が有名ですが、そちらについては既に特定し、対策済みでした。 THP と Hadoop に関係については下記 Blog が詳しいです。 Transparent Huge Pages and Hadoop Workloads 今回は THP ではなく、 "zone_reclaim_mode" の設定による性能劣化について、現象から原因特定に至るまでの経緯と、推奨する設定について解説します。 現象 観測された現象について簡単に箇条書きします。 CPU user が 5% 程度
August 9, 2013 Volume 11, issue 7 PDF NUMA (Non-Uniform Memory Access): An Overview NUMA becomes more common because memory controllers get close to execution units on microprocessors. Christoph Lameter, Ph.D. NUMA (non-uniform memory access) is the phenomenon that memory at various points in the address space of a processor have different performance characteristics. At current processor speeds,
The motherboard of an HP Z820 workstation with two CPU sockets, each with their own set of eight DIMM slots surrounding the socket Non-uniform memory access (NUMA) is a computer memory design used in multiprocessing, where the memory access time depends on the memory location relative to the processor. Under NUMA, a processor can access its own local memory faster than non-local memory (memory loc
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Kernel.org git repositories Git repositories hosted at kernel.org index NameDescriptionOwnerIdleLinks pub/scm/bluetoothbluez.gitBluetooth protocol stack for LinuxMarcel Holtmann81 min.summarylogtree sbc.gitBluetooth low-complexity, subband codec (SBC) libraryMarcel Holtmann5 monthssummarylogtree pub/scm/develpahole/pahole.gitpahole and other type info toolsDWARVES group5 hourssummarylogtree sparse
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