Re: [PATCH] speed up SATA

From: Jeff Garzik
Date: Sun Mar 28 2004 - 15:04:09 EST

Nuno Silva wrote:
With this kind of control we could have /etc/init.d/io-optimize that
paused the startup for 10 seconds and tests every device|controller in
fstab and optimizes according to the .conf file for latency or speed...
Or a daemon that retrieves statistics and adjusts the policies every minute?

Also, everybody says "do it in userland". This is doing (some of) it in
userland :)

An iotune daemon that sits in userland -- probably mlockall'd into memory -- would be fun. Like the existing irqbalance daemon that Red Hat (disc: my employer) ships, "iotuned" could run in the background, adjusting policies every so often. It would be a good place to put some of the more high-level "laptop mode" or "high throughput mode" tunables, so that the user wouldn't have to worry about the minute details of such things.

Just watch the IO statistics and tweak the queue settings... Gotta make sure the queue settings don't get tweaked beyond what the hardware can do, though.

A good iotune daemon would probably have to pay attention to various VM statistics as well, since the VM is often the one that decides when to start writing out stuff... such an app could (quite justifiably) mushroom into a io-and-vmtune daemon.

This is a side issue from the topic of finding a decent in-kernel default, of course...


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