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Date:      Tue, 27 Jul 2010 15:52:06 -0500
From:      Adam Vande More <amvandemore@gmail.com>
To:        Debacker <debackerl@gmail.com>
Cc:        Andrew Gould <andrewlylegould@gmail.com>, freebsd-questions@freebsd.org
Subject:   Re: Real-Time Video Recording (ionice equivalent)
Message-ID:  <AANLkTimg2T9smg0hcdnsdyNBur2569dU0L_6eA-fLZTG@mail.gmail.com>
In-Reply-To: <AANLkTimwplb2_HptPh0e6KEQnr4HqYxDPe5vD4Uw8OIf@mail.gmail.com>
References:  <AANLkTinqwCSzoCdEnrSoXN1jkpoIGmESgbMsI3JFB5YF@mail.gmail.com> <AANLkTinQx3Myo06ed7Q7Ou_r3tepGGYQFbfhYNJbpa6T@mail.gmail.com> <AANLkTimwplb2_HptPh0e6KEQnr4HqYxDPe5vD4Uw8OIf@mail.gmail.com>

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On Tue, Jul 27, 2010 at 2:29 PM, Debacker <debackerl@gmail.com> wrote:

> Of course, just like you could put real-time processes in one CPU, and
> normal processes on another to avoid implement complex algorithms.
> While your solution is pragmatic, I would like to know if there are "clean"
> ways to do it. If not, this would be a documented use case to why would
> anyone actually need an I/O scheduler.
>

First, top-posting on this list is considered rude.  Please don't do that.

If you're running 8.1, try "man gsched", it's new and haven't tried it.

Other than that, the traditional way would be to give higher priority to the
process that needs it.  It's the poor man's io scheduler, but it generally
does work well.

If you have lots of concurrent io and are running a UFS file-system,
consider running gjournal as it scales those requests better.

Also if you're hardware supports it, NCQ is available via the ahci and a few
other modules.  It will make your requests more efficient.

-- 
Adam Vande More



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