Re: test9 not using buffers

From: Alexander Viro (
Date: Wed Oct 11 2000 - 20:04:07 EST

On Thu, 12 Oct 2000, Tom Holroyd wrote:

> Alpha DP264 (UP), SCSI, floppy
> If I do a dd if=/dev/zero of=/tmp/moo count=100000, I don't see any
> increase in buffers, as reported by vmstat. Furthermore, if I read from
> /dev/fd0, it used to buffer the whole thing, so a second read would be
> fast -- now it hits the floppy again.

a) /dev/zero: character device, no buffers used at all. /tmp/moo: regular
file, data goes into pagecache, so all buffers you will get out of it
will be for indirect blocks. Assuming 4Kb filesystem that would be about
13Kb worth. Userland buffer is in pagecache too, indeed.

b) invalidate on last close.

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