NetNews Usenet Archive 1992 #27/NN_1992_27.iso/spool/comp/benchmar/1693

Internet Message Format | 1992-11-15 | 1.9 KB

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From: [e-mail] (Rogier Wolff)
Subject: Re: Disk performance issues, was IDE vs SCSI-2 using iozone
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Organization: Delft University of Technology, Dept. of Electrical Engineering
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Date: Sun, 15 Nov 1992 23:48:41 GMT
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[e-mail] (John Bass) writes:

>Caching all writes is also highly productive ... editor writes out
>C source, to be read by C compiler which writes object module read
>by linker which writes the executable to read by system loader when
>the user tests. The cycle repeats, deleting ALL files created by the
>cycle .... if you hold the I/O long enough ... it really isn't I/O
>after all.

I was looking at the Linux sources a few days ago, and found that
indeed if a file is deleted before it's blocks are written to disk,
the blocks in the buffer are "un-dirtied", and thus never written
to disk.

This in contrast to DOS where the hyperdisk disk-cache program
doesn't have the knowledge that the OS has: I can copy about 1Mb
of data to floppy, and delete them well before hyperdisk finishes
writing the data to the floppy. All data gets written unnecessarily
to the disk.

Anyway, it takes a well written OS to actually benefit from this.


                    Roger.
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