# Concurrent files access and responsiveness



## tobe (Feb 28, 2009)

Hi BSD people,

Just like any other OS i've used so far, my FreeBSD setup (7.1 stable) lacks of responsiveness when more than one application access the filesystem.

Nowadays, CPUs are fast, and running a few processes in parallel is barely noticeable, but when a few processes access the filesystem concurrently, it become really noticeable.

For example, when i'm running Transmission with a few torrents active, my whole system is slowed down while Transmission is only using less than 10% of my CPU. (My internet connection is rather fast, 100 mbits/s, so most of the time my download speed is around 1 mbytes/s).

So i was wondering, is there any priority management for file access (like 'nice' for the processes) ? Can i run an application and tell the system that this application will access files with a lower priority ?

Thanks,
Jean-Baptiste


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## plamaiziere (Mar 1, 2009)

tobe said:
			
		

> Hi BSD people,
> 
> So i was wondering, is there any priority management for file access (like 'nice' for the processes) ? Can i run an application and tell the system that this application will access files with a lower priority ?



No there is no such facility. There is a "geom scheduler" in developement, but I didn't try it.

See:
http://lists.freebsd.org/pipermail/freebsd-stable/2009-January/047597.html


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## Djn (Mar 1, 2009)

Ooh, that scheduler looks like a very good idea. I'll have to test it at some point.


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## tobe (Mar 1, 2009)

plamaiziere said:
			
		

> No there is no such facility. There is a "geom scheduler" in developement, but I didn't try it.
> 
> See:
> http://lists.freebsd.org/pipermail/freebsd-stable/2009-January/047597.html



Wow it looks really interesting, thanks !

edit:
More information here:
http://algo.ing.unimo.it/people/paolo/disk_sched/


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## ArtemD (Mar 5, 2009)

tobe said:
			
		

> Wow it looks really interesting, thanks !
> 
> edit:
> More information here:
> http://algo.ing.unimo.it/people/paolo/disk_sched/



Looks interesting. If it's stable I hope it gets merged into kernel.


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