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Date: Sun, 13 Feb 2005 03:21:29 -0500
From: David Schultz <das@FreeBSD.ORG>
To: Jason Henson <jason@ec.rr.com>
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cc: freebsd-hackers@FreeBSD.ORG
Subject: Re: malloc vs ptmalloc2
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On Sun, Feb 13, 2005, Jason Henson wrote:
> I saw on a few of the lists here how linux uses ptmalloc2 and it  
> outperforms bsd's malloc.  I tried to do some research into it and  
> found PHK's pdf on it and it seems bsd's malloc was ment to be ok in  
> most every situation. Because of this it shines when primary storage is  
> seriously over committed.
> 
> So here is my question, I use FreeBSD as a desktop and never ever use  
> swap(I just don't stress my system enough?), can I use ptmalloc in  
> stead of malloc?  Like defining SCHED_ULE instead of SCHED_4BSD.  Can  
> the system malloc be switched out?  

With a little bit of work, you should be able to replace
src/lib/libc/stdlib/malloc.c.  ptmalloc is much more heavyweight,
but it would probably do better in cases where you have a large
number of threads doing a massive number of malloc/free operations
on a multiprocessor system.  Other than that, I don't know enough
details about ptmalloc to speculate, except to say that for most
real-world workloads on modern systems, the impact of the malloc
implementation is likely to be negligible.  Of course, test
results would be interesting...