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SubjectRE: Disk priorities...
Date
I wasn't so worried about a 'trick' in this situation.  I'm running
all the processes. Three of them were clean up and do book-keeping
processes that I didn't care so much about when they ended. The foreground
process was also mine -- so I'm not so worried about cheating at this
point.

Specifically, I'm talking about 'nice'd "down" processes -- things
I want to take lower priority over what I am doing in foreground. I'd
like that to apply to disk, cpu and network usage. CPU's are getting so
fast these days such that the bottlenecks are more and more becoming
how fast can you get the data to them. Disk drives with ms seek times
are a problem. The seek times on drives.

I don't think the disk ops have been tuned to minimize seeking,
have they? -- that'd be a good algorithm to use for same-disk-priority
disk requests.

We'd have to start thinking about disks as 'processors' and have
per-disk queues that are prioritized with the cpu constantly feeding
1 event ahead of the one the disk is currently processing, that way the
cpu can reorder disk operations as needed.

-l

> -----Original Message-----
> From: Alexander Viro [mailto:viro@math.psu.edu]
> Sent: Sunday, October 01, 2000 1:52 PM
> To: Rik van Riel
> Cc: LA Walsh; lkml
> Subject: Re: Disk priorities...
>
>
>
>
> On Sun, 1 Oct 2000, Rik van Riel wrote:
>
> > > And if you mean reads... Good luck propagating the originator
> > > information.
> >
> > Isn't it the case that for most of the filesystem
> > reads the current process is the one that is the
> > originator of the request ?
>
> Not true for metadata (consider the access to indirect blocks done by
> pageout, for one thing). Besides, even for data it's wide open to abuse -
> it doesn't take much to trick another process into populating the caches
> for you.
>
>
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