Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.1 6/24/83; site alice.UUCP
Path: utzoo!watmath!clyde!burl!ulysses!allegra!alice!ark
From: ark@alice.UucP (Andrew Koenig)
Newsgroups: net.unix
Subject: Re: get size of malloc'd object
Message-ID: <5704@alice.uUCp>
Date: Wed, 25-Jun-86 09:17:08 EDT
Article-I.D.: alice.5704
Posted: Wed Jun 25 09:17:08 1986
Date-Received: Fri, 27-Jun-86 06:56:14 EDT
References: <139@uwslh.UUCP>
Organization: Bell Labs, Murray Hill
Lines: 16

> One nasty efficiency quirk probably ought to be mentioned.  The schemes which
> add extra user information to remember the size of the object are okay,
> modulo some pointer alignment details.  Care with the size of the objects
> may be needed if you are allocating lots of them, though.  Some memory
> allocators allocate things in fixed sizes, such as power-of-two minus some
> internal overhead. If a program is allocating funny sized buffers scaled to
> cooperate with brain damaged allocators, and then adds extra overhead, the
> resulting size may cause poor allocators to waste lots of space.  Of course,
> 'knowing' the size of blocks actually allocated is not portable. But if you
> are tight on address space or physical memory, it could matter.

Translated into English, this says:

	Some memory allocators are broken.  Thus we should all
	warp our programs into forms that work well with these
	broken memory allocators.