Messages in this thread | | | Date | Mon, 26 Jul 1999 21:54:58 +0200 (CEST) | From | Rik van Riel <> | Subject | Re: (disk/cpu) kernel performance problem |
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On Mon, 26 Jul 1999, Gerald Aigner wrote:
> While optimizing the program I discovered that disk I/O > performance in Linux could be improved substantially. In > particular, there are two main problems: > > 1) The kernel copies data many times before it ends up in user > space.
I'm very sorry, but you seem to be too late. This problem is (at least partially) fixed in the newer 2.3 kernels...
> 2) Using mmap doesn't help because it serializes I/O within a single > process (you can't read simultaneously from two disks).
A single process uses a single thread of control, and yes, we do readahead over RAID0 sets...
If you want to do true async I/O, you can just use the interface glibc gives you to do that.
Rik -- Open Source: you deserve to be in control of your data. +-------------------------------------------------------------------+ | Le Reseau netwerksystemen BV: http://www.reseau.nl/ | | Linux Memory Management site: http://www.linux.eu.org/Linux-MM/ | | Nederlandse Linux documentatie: http://www.nl.linux.org/ | +-------------------------------------------------------------------+
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