[gofetch.git] / test / expected / LWN / 0000763603.header.html

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	<h2><a href='0000763603.html'>[$] Measuring (and fixing) I/O-controller throughput loss</a></h2>
	<div class='details'>([Kernel] Aug 29, 2018 21:20 UTC (Wed) (corbet))</div>
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		Many services, from web hosting and video streaming to cloud storage, need to move data to and from storage. They also often require that each per-client I/O flow be guaranteed a non-zero amount of bandwidth and a bounded latency. An expensive way to provide these guarantees is to over-provision storage resources, keeping each resource underutilized, and thus have plenty of bandwidth available for the few I/O flows dispatched to each medium. Alternatively one can use an I/O controller. Linux provides two mechanisms designed to throttle some I/O streams to allow others to meet their bandwidth and latency requirements. These mechanisms work, but they come at a cost: a loss of as much as 80% of total available I/O bandwidth. I have run some tests to demonstrate this problem; some upcoming improvements to the [1]bfq I/O scheduler promise to improve the situation considerably.<br/><br/><br/><br/>[1] https://lwn.net/Articles/601799/
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	1	<!DOCTYPE html>
	2	<html>
	3	<head>
	4	<meta http-equiv='content-type' content='text/html; charset=utf-8'>
	5	<meta name='viewport' content='width=device-width, initial-scale=1.0'>
	6	<style type='text/css'>
	7	body { margin: 1em 15%; }
	8	</style>
	9	</head>
	10	<body>
	11	<div class='story-header'>
	12	<h2><a href='0000763603.html'>[$] Measuring (and fixing) I/O-controller throughput loss</a></h2>
	13	<div class='details'>([Kernel] Aug 29, 2018 21:20 UTC (Wed) (corbet))</div>
	14	<br/>
	15	<div class='content' style='text-align: justify'>
	16	Many services, from web hosting and video streaming to cloud storage, need to move data to and from storage. They also often require that each per-client I/O flow be guaranteed a non-zero amount of bandwidth and a bounded latency. An expensive way to provide these guarantees is to over-provision storage resources, keeping each resource underutilized, and thus have plenty of bandwidth available for the few I/O flows dispatched to each medium. Alternatively one can use an I/O controller. Linux provides two mechanisms designed to throttle some I/O streams to allow others to meet their bandwidth and latency requirements. These mechanisms work, but they come at a cost: a loss of as much as 80% of total available I/O bandwidth. I have run some tests to demonstrate this problem; some upcoming improvements to the [1]bfq I/O scheduler promise to improve the situation considerably.<br/><br/><br/><br/>[1] https://lwn.net/Articles/601799/
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