Linux-kernel mailing list archive 1999-25,: Re: Fw: FENRIS (nwfs) Source Code Now Available.

# Re: Fw: FENRIS (nwfs) Source Code Now Available.

Jeff Merkey (jmerkey@timpanogas.com)
Mon, 21 Jun 1999 12:00:14 -0600

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Ingo,

I'll look at 2.2 and compare it. Right now I'm working on a code drop for
today. I apologize if I cannot jump right on this for you, but I am trying
to get some stuff Alan Cox asked me to check in finished. As soon as this
is finished then I'll go through the code. Which files is this in in 2.2?

Thanks

Jeff

----- Original Message -----
From: Ingo Molnar <mingo@chiara.csoma.elte.hu>
To: Jeff Merkey <jmerkey@timpanogas.com>
Cc: <linux-kernel@vger.rutgers.edu>
Sent: Monday, June 21, 1999 11:15 AM
Subject: Re: Fw: FENRIS (nwfs) Source Code Now Available.

>
> On Mon, 21 Jun 1999, Jeff Merkey wrote:
>
> > > [...] Also, Windows NT has some pretty nifty stuff
> > > in it's file system architecture for SMP. The way the VM Cache
manager is
> > > implemented in Windows NT is nothing short of genius. By caching MCB
> > > allocation run information (NT reads and writes files by constructing
MCB
> > > lists in memory, which are in-memory descriptors of a file's
contiguous
> > > sector runs), this gives NT the ability to perform some fairly
> > > sophisticated read-ahead and cache predication operations for random
> > > access as well as sequential access files. This architecture is also
> > > superior for SMP operations. MCB lists can basically be sent in a
> > > parallel fashion to the IO subsystem and transacted in parallel. [...]
>
> would you mind comparing it to what Linux 2.3.7's page cache does? That
> one has pagecache design pretty close to 'genius' as well, and not only on
> paper :) On a 4-ways Xeon we scale read performance ~380%, which is
> basically linear:
>
> single-process reads done on the same 60k file:
>
> [root@moon fileben]# ./fileben ./FILE 60000 1 1 1
> READ: 273.76 MB/sec
>
> 4-process read()s done on the same 60k file:
>
> [root@moon fileben]# ./fileben ./FILE 60000 4 1 1
> READ: 258.16 MB/sec
> READ: 258.09 MB/sec
> READ: 258.04 MB/sec
> READ: 258.20 MB/sec
>
> part of the rather dramatic speedup is also a new mechanizm: the new
> pagecache now also caches 'filesystem physical block addresses', which
> allows us to skip a costy lookup of filesystem metadata for every block of
> file read() or written.
>
> -- mingo
>
>

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- Next message: Matthew Jacob: "Re: System unique identifier....."
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- Maybe in reply to: Jeff Merkey: "Fw: FENRIS (nwfs) Source Code Now Available."
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