*BSD News Article 54796


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From: shovey@buffnet.net (steve hovey)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: INND1.4+MMAP=BROKEN MESS
Date: 8 Nov 1995 13:48:46 GMT
Organization: BuffNET
Lines: 33
Distribution: world
Message-ID: <47qcfu$4r8@buffnet2.buffnet.net>
References: <46ldvj$l3c@buffnet2.buffnet.net> <imzqekgzmt.fsf@hidden.cs.uidaho.edu> <472u66$dpo@blackbush.xlink.net> <47f3gf$2gu@atlas.uniserve.com> <47m335$eu3@buffnet2.buffnet.net> <47m8kq$gqq@atlas.uniserve.com>
NNTP-Posting-Host: buffnet3.buffnet.net
X-Newsreader: TIN [version 1.2 PL2]

Tom Samplonius (tom@uniserve.com) wrote:
: In article <47m335$eu3@buffnet2.buffnet.net>, root@buffnet.net says...
: >:   I've seen this problem with mmap and INN too.  Basically, the active 
: file wasn't 
: >: staying current, and the hi index value was dropping behind, causing 
: "cant symlink" 
: >: errors.
: >
: >:   I believe the problem is related to swapping.  On heavy swapping 
: systems, it will 
: >: happen a lot.  It appears that when the mmap'ed active is paged out, 
: sometimes it isn't 
: >: written back to the file, but when it is paged in, it is read back from 
: the file.

:   A bug was found a couple of days ago, in the msync code.  It is quite 
: likely the cause of the failed active file updates that happen with mmap 
: under innd.  A partial fix is in -current.

:   For now, just run innd without mmap.  On a FreeBSD system there is almost 
: no performance difference between read/write and mmap anyway (due to unified 
: disk cache and VM system).

: Tom

Im told by other admins that MMAP doesnt work with BSDI either - and I 
did note that I wasnt experiencing the performance penalties that my 
peers said I would without MMAP (they said INN slows badly if you history 
file is over 20MB - mine is over 100MB).

-------------------------------------------------------------
Steve Hovey -- shovey@buffnet.net
 	       root@buffnet.net