Path: utzoo!mnetor!uunet!lll-winken!lll-tis!ames!amdahl!nsc!taux01!amos
From: amos@taux01.UUCP (Amos Shapir)
Newsgroups: comp.unix.wizards
Subject: Delayed writes on removed files
Message-ID: <595@taux01.UUCP>
Date: 26 Apr 88 22:03:11 GMT
Organization: National Semiconductor (Israel) Ltd. Home of the 32532
Lines: 15
Hdate: 10 Iyar 5748


Here is something new  for a change: When a file  is removed, its blocks
are released to  the free list. If  any writes were done,  some of these
blocks may  still be in  the buffer pool,  waiting for a  delayed write.
When such  buffers are reallocated,  they will  be written to  the disk,
even though their contents are no longer relevant.

The systems I have checked - 4.2  and sysV.3 - make no effort to prevent
this. It seems  that in an environment in which  many files are created,
written to, and then discarded (e.g. compilation) preventing unnecessary
writes  to  disk  may  have  a  significant  effect  on  overall  system
performance. Does anyone know of a system that does this, and how?
-- 
	Amos Shapir			(My other cpu is a NS32532)
National Semiconductor (Israel)
6 Maskit st. P.O.B. 3007, Herzlia 46104, Israel  Tel. +972 52 522261
amos%taux01@nsc.com  34 48 E / 32 10 N