Subject: Re: NCR Driver Problems
To: None <Chris_G_Demetriou@niagara.nectar.cs.cmu.edu,>
From: proprietor - Foo Bar And Grill <jgraham@defender.VAS.viewlogic.com>
Date: 01/31/1996 10:19:55
So which part of the system needs to handle the concurrency? Does FFS
need to be rewhacked, or what?
#define AUTHOR "Chris_G_Demetriou@NIAGARA.NECTAR.CS.CMU.EDU (Chris_G_Demetriou@NIAGARA.NECTAR.CS.CMU.EDU)"
* People who say "use disksort" are missing something: concurrency.
* There's a lot of literature out there, that's been put out recently,
* about the fact that exposing I/O concurrency to the OS, and to the
* hardware wins significantly.
* In the recent SOSP paper that my group did, we saw some occasionally
* quirky -- but always better -- performance by exposing more concurrency
* to the drive(s). (The one particular case i can think of, that i
* think was mentioned in that paper was a case where we were doing grep
* string * for the files in one manual section, and disclosing our future
* file accesses to the OS via hints, so that it would prefetch the data.
* w/ one request outstanding at the drive, we got horrible performance,
* with many, we got great performance... turns out that the layout
* of the files on-disk -- done by the FFS -- was EXACTLY OPPOSITE
* optimal, because of the fact that the files were added to the
* directory in almost reverse order.)
#undef AUTHOR /* "Chris_G_Demetriou@NIAGARA.NECTAR.CS.CMU.EDU (Chris_G_Demetriou@NIAGARA.NECTAR.CS.CMU.EDU)" */
I'm really a software toolsmith and a musician by trade, but nobody really
needs a software toolsmith much, and the music industry is so cutthroat
that it would probably do me in. So I do systems administration on the
side as a hobby. Funny that my hobby finds more work than either of my