From owner-cvs-usrsbin  Tue Jan 10 13:43:35 1995
Return-Path: cvs-usrsbin-owner
Received: (from root@localhost) by freefall.cdrom.com (8.6.9/8.6.6) id NAA04985 for cvs-usrsbin-outgoing; Tue, 10 Jan 1995 13:43:35 -0800
Received: from godzilla.zeta.org.au (godzilla.zeta.org.au [203.2.228.34]) by freefall.cdrom.com (8.6.9/8.6.6) with ESMTP id NAA04979; Tue, 10 Jan 1995 13:43:14 -0800
Received: (from bde@localhost) by godzilla.zeta.org.au (8.6.9/8.6.9) id IAA25273; Wed, 11 Jan 1995 08:42:53 +1100
Date: Wed, 11 Jan 1995 08:42:53 +1100
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199501102142.IAA25273@godzilla.zeta.org.au>
To: CVS-commiters@freefall.cdrom.com, cvs-usrsbin@freefall.cdrom.com,
        phk@freefall.cdrom.com
Subject: Re: cvs commit: src/usr.sbin/kvm_mkdb kvm_mkdb.c nlist.c
Sender: cvs-usrsbin-owner@FreeBSD.org
Precedence: bulk

>  Modified:    usr.sbin/kvm_mkdb kvm_mkdb.c nlist.c
>  Log:
>  Speed kvm_mkdb up by a factor 5 or thereabout.  Rewrote all the fseek/fread
>  nonsense to use a mmap'ed file instead and told the DB/hash what we are up to.
>  
>  dev_mkdb could maybe benefit from the same treatment.

I speeded it up by a factor of 10 or thereabouts by removing write-through
of full blocks in ufs.  (kvm, and potentially anything that does a lot of
random access, writes to the same blocks many times.)  Your fix works
because there is no way to tell when an mmap'ed block is full, so the
write-through pessimization cannot be applied.

Bruce