Kernel of Truth | LINUX Unplugged 113

Kernel of Truth | LINUX Unplugged 113

Performance tips for keeping your Linux install running like new, some basic tricks & some advanced tips.

Why Microsoft’s new Surface Book might be able to run Linux & we reflect on the larger issues behind the recent public exits from the Linux Kernel development team & more!

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Ting


DigitalOcean


Linux Academy

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World Without Linux Episode #1: What’s the Name of That Song?

Remembering who sings your favorite song is a lot harder without Linux.

N1 is a new open source e-mail app from Created by Nylas Inc., built using React, Flux, and Electron.

Like a web-browser or modern text editor, N1 is designed to be built on and improved through extensions.

Rover Log

TING

Surface Book – The ultimate laptop

Surface Book

Ultra-thin, meticulously crafted, with incredible screen resolution. This is the ultimate laptop.

The latching mechanism has a wide electrical connector, no doubt PCIe-based to facilitate communication between the GPU and the rest of the system.

DigitalOcean

Keeping Linux Performing Well.

Tips and tricks for keeping your Linux box in top performance.

Creating your swap files on a separate disk can also help quite a bit, especially if your machine swaps frequently. It happens if you do not have enough RAM for your environment. Using KDE with all the features and applications that come along may require several GiB of memory, whereas a tiny window manager with console applications will perfectly fit in less than 512 MiB of memory.

Although the extent-based nature of XFS and the delayed allocation strategy it uses significantly improves the file system’s resistance to fragmentation problems, XFS provides a filesystem defragmentation utility (xfs_fsr, short for XFS filesystem reorganizer) that can defragment the files on a mounted and active XFS filesystem. It can be useful to view XFS fragmentation periodically.

The kernel supports different schedulers for storage disk in-/output (IO). These are the CFQ scheduler (Completely Fair Queuing), the NOOP and Deadline. Another, the BFQ (Budget Fair Scheduler) is available in the linux-zen kernel.

A HDD has spinning disks and head that move physically to the required location. Such structure leads to following characteristics:

  • random latency it quite high, for modern HDD it is ~10ms (ignoring a disk controller write buffer).
  • sequential access provides much higher throughput. In this case head needs to move less distance.

In case if we have a lot of running processes that make IO requests to different parts of storage (i.e. random access) then we can expect that a disk handles ~100 IO requests per second. Because modern systems can easily generate load much higher than 100 requests per second we have a queue of requests that have to wait for access to the storage. One way to improve throughput is to linearize access, i.e. order waiting requests by its logical address and always choose the closest request. Historically this was the first Linux IO scheduler called elevator scheduler.

One of the problems with the elevator algorithm is that it makes suffer processes with sequential access. Such processes read a block of data then process it for several microseconds then read next block and so on. The elevator scheduler does not know that the process is going to read another block nearby and, thus, moves to another request at some other location. To overcome the problem anticipatory IO scheduler was added. For synchronous requests this algorithm waits for a short amount of time before moving to another request.

While these schedulers try to improve total throughput they also might leave some unlucky requests waiting for a very long time.

Linux Academy

Going my own way

In the end it’s a mixture of just being tired of dealing with the crap associated with Linux development and realising that by continuing to put up with it I’m tacitly encouraging its continuation, but I can’t be bothered any more. And, thanks to the magic of free software, it turns out that I can avoid putting up with the bullshit in the kernel community and get to work on the things I’m interested in doing. So here’s a kernel tree with patches that implement a BSD-style securelevel interface. Over time it’ll pick up some of the power management code I’m still working on, and we’ll see where it goes from there. But, until there’s a significant shift in community norms on LKML, I’ll only be there when I’m being paid to be there. And that’s improved my mood immeasurably.

Closing a door | The Geekess

I am no longer a part of the Linux kernel community.

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