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Date: Mon, 6 Feb 2006 15:56:34 +0100 (MET)
From: Jan Engelhardt <jengelh@linux01.gwdg.de>
To: Arjan van de Ven <arjan@infradead.org>
cc: Mark Lord <lkml@rtr.ca>, Ulrich Mueller <ulm@kph.uni-mainz.de>,
       Herbert Poetzl <herbert@13thfloor.at>, linux-kernel@vger.kernel.org,
       Jens Axboe <axboe@suse.de>, Linus Torvalds <torvalds@osdl.org>,
       Byron Stanoszek <gandalf@winds.org>, Ingo Molnar <mingo@elte.hu>,
       Andrew Morton <akpm@osdl.org>
Subject: Re: [PATCH ]  VMSPLIT config options (with default config fixed)
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>> >> What userspace programs do depend on it?
>> >
>> >there is a lot of userspace that assumes they can do 2Gb or even close
>> >to 3Gb of memory allocations. Databases, java, basically anything with
>> >threads. Sure for most of these its a configuration option to reduce
>> >this, but that still doesn't mean it's a good idea to change from the
>> >existing behavior...
>> > 
>> Not to mention that these (almost(*)) fail anyway when you have less than 2 
>> GB of RAM.
>
>it's not really overcommit... it can also be file mmaps or shared mmaps
>of say tmpfs files (the later is common with oracle actually)
>

So, just as I did in the sample patch, the manual split shall depend on 
EMBEDDED. Those who run fat databases with big malloc/mmap assumptions 
don't probably belong to the group using CONFIG_EMBEDDED.


Jan Engelhardt
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