Tag Info

Hot answers tagged

53

It simply gives an illusion of speed to programs that don't actually have to wait until a write is complete. Mount your filesystems in sync mode (which gives you your instant writes) and see how slow everything is. Sometimes files exist only temporarily... a program does some bit of work and deletes the file right after the work is done. If you delayed ...


37

What's the philosophy behind such an approach? Efficiency (better usage of the disk characteristics) and performance (allows the application to continue immediately after a write). Why isn't the data written at once? The main advantage is the OS is free to reorder and merge contiguous write operations to improve their bandwidth usage (less ...


23

Asynchronous, buffered I/O was in use before Linux and even before Unix. Unix had it, and so have all its offshoots. Here is what Ritchie and Thompson wrote in their CACM paper The UNIX Time-Sharing System: To the user, both reading and writing of files appear to be synchronous and unbuffered. That is immediately after return from a read call the ...


13

Many good answers, but let me add one other thing... Remember that Unix is a multi-process and multi-users system, so potentially many users would be trying to do file-operations (esp. writes) at (almost) the same time. With old slow hard-disks - perhaps mounted over the network - this would not only take time (for which the programs would basically ...


10

It is not specific to Linux, and it is called the page cache (which Linux does quite well). See also http://linuxatemyram.com/; so if a file is written, then read again a few seconds later, very often no disk I/O is needed. The main advantage is that on many systems, there is a lot of RAM, and some of it can be used as a cache by the kernel. So some files ...


7

Spinning platters are slower than RAM. We use caching of reads/writes to 'hide' this fact. The useful thing about write IO is that it doesn't require disk IO to happen immediately - unlike a read, where you can't return data to the user until the read completes on the disk. Thus writes operate under a soft time constraint - as long as our sustained ...


5

None of the other answers mentioned delayed allocation. XFS, ext4, BTRFS, and ZFS all use it. XFS has been using it since before ext4 existed, so I'll use it as the example: XFS doesn't even decide where to put data until writeout. Delayed-allocation gives the allocator much more information to base its decisions on. When a file is first being written, ...


3

All the other answers here are at a minimum mostly correct for the normal case, and I would recommend reading any of them before mine, but you mentioned dd and dd has a typical use case that May not involve write caching. Write caching is primarily implemented at the filesystem level. Raw devices do not normally do write caching (multiple device drivers such ...


2

It trades a small amount of reliability for a great increase in throughput. Suppose, for example, a video compressing program. With delayed write ("write back"): spend 10ms compressing frame issue write frame to disk wait 10ms for disk to acknowledge write complete GOTO 1 Versus spend 10ms compressing frame issue write frame to disk (completes in ...


2

The kernel and the NIC communicate the same way the kernel (specifically, a device driver, which is part of the kernel) communicates with any other device (e.g., serial communications device (like keyboard, mouse, or RS232), disk (or disk-like mass storage device), display, security token, etc.) – they talk directly to each other.  So, yes, this happens ...


2

The philosophy is unsafe-by-default. There are two reasonable and obvious strategies possible: flush writes to disk immediately or delay writing. UNIX historically chose the latter. So get safety, you need to call fsync afterwards. However, you can specify safety upfront by mounting a device with option sync, or per-file by opening them with O_SYNC. ...


1

There is probably a line in /etc/apt/sources.list (or in one of the files in /etc/apt/sources.lists.d/ starting with deb cdrom ... Comment this line out and Debian wont try to install packages from this disc.


1

In many applications, storage devices will be intermittently busy reading data. If a system is always able to defer writes until a time when the storage device isn't busy reading data, then from an application's point of view the writes will take zero time to complete. The only situations in which writes would not be instantaneous would be when: Write ...


1

This is only a partial answer. Other folks should feel free to copy this as a basis for their answers. Touch screens input devices can be opened as simple mice, or with full access to their touch-screeniness via /dev/input/... and evdev stuff. You need to get your X server to use the input device as a touchscreen. The X server translates touch-screen ...


1

The non-live variant at http://cdimage.debian.org/cdimage/unofficial/non-free/cd-including-firmware/8.1.0/amd64/iso-cd/firmware-8.1.0-amd64-netinst.iso will work better when you're trying to install with firmware.


1

Stephen's answer is correct, there is an install image WITH firmware. I would have posted (version-independant) this link though: http://cdimage.debian.org/cdimage/unofficial/non-free/cd-including-firmware/current/amd64/iso-cd/ . This folder always has the latest release image. If you dont want to download the image again or have finished the installation ...


1

Wine doesn't support USB yet, and it also doesn't support installing device drivers. So no, you can't use it to install Logitech drivers for Windows on Linux. On Linux systems most device drivers are already provided by the kernel, and nothing needs to be installed. If you're having trouble using your devices on Linux you can ask a new question with the ...


1

Solution A Google for "lenovo g500 touchpad linux" returned the Laptops and Netbooks Support Page for Lenovo G500, Setting the Component Dropdown to Mouse & Keyboard yields the following: Touchpad Driver (Synaptics, Elan) Version: 16.4.1.0 /11.4.14 .1 Date: 5/26/2013 Synaptics is all we needed from the entry to determine the correct driver. ...


1

I've just found out that your chip is actually rtl8192eu. As far as I know, there is no driver for it in Ubuntu's repo. However, as v0yAgEr mentioned on OSMC forums, there is driver for that chip works for kernel version 3.18 on GitHub. I modified v0yAgEr's tutorial to a way hopefully would work for you: Install build-essential: From the computer have ...



Only top voted, non community-wiki answers of a minimum length are eligible