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Date:      Thu, 14 Dec 2017 22:39:18 +0700
From:      Eugene Grosbein <eugen@grosbein.net>
To:        Konstantin Belousov <kostikbel@gmail.com>
Cc:        John Baldwin <jhb@FreeBSD.org>, Conrad Meyer <cem@FreeBSD.org>, src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   Re: svn commit: r326758 - in head/sys/i386: conf include
Message-ID:  <5A329B26.9040504@grosbein.net>
In-Reply-To: <20171214152324.GJ2272@kib.kiev.ua>
References:  <20171211091943.GF2272@kib.kiev.ua> <5A2E5D44.9030904@grosbein.net> <4a9c76c9-8063-9420-b198-14487b089840@FreeBSD.org> <5A30378A.3040609@grosbein.net> <e2c426c3-41ed-2dd8-c5d4-15c60d8f7303@FreeBSD.org> <5A3261BD.5050404@grosbein.net> <20171214115149.GC2272@kib.kiev.ua> <5A3268E9.506@grosbein.net> <20171214122659.GF2272@kib.kiev.ua> <5A327597.3010300@grosbein.net> <20171214152324.GJ2272@kib.kiev.ua>

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On 14.12.2017 22:23, Konstantin Belousov wrote:

>>> Sigh. This would make i386 even less usable for everybody, perhaps
>>> except you. Because default 3G of UVA is too small for some common tasks
>>> (thanks clang, but also e.g. pypy), and you reduce the user address
>>> space even more.
>>
>> Those who need 3GB of UVA within single process should not use 32 bit system in first place, should they?
> 
> Why do you even consider it acceptable to break the configuration just
> because you are not interested in the workload ?

I do not consider it is acceptable. I'm trying to find compromise.

> 3G cumulative VA does not translate into 3G of usable addresses: the bss
> is reserved, the address space is fragmented due to need of growing
> stack to not conflict with mmaped regions. As result, applications get
> slightly less than 2G usable without tricks, and to apply the tricks
> apps must know details of the AS layout, i.e. breaking the portability.
> 
> 386 arch configuration is not perfect but it provides the main intended
> service of general-purpose workstation, with some limitation caused by
> 32bit of address space being somewhat low for modern code. Appliance
> flavoring of the default 386 config is unacceptable.  Keep your tweaks
> local.

Do you think that kstack overflow of general-purpose workstation using NFS
or IPv6 or WiFi with SCTP is OK? I do not.




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