From: Marvin Justice <mjustice@austin.rr.com>
To: "H. Peter Anvin" <hpa@zytor.com>, mjustice@austin.rr.com
Cc: linux-kernel@vger.kernel.org
Subject: Re: highmem question
Date: Fri, 7 Dec 2001 19:53:47 -0600 [thread overview]
Message-ID: <01120719534703.00764@bozo> (raw)
In-Reply-To: <Pine.LNX.4.30.0112071404280.29154-100000@mustard.heime.net> <01120719300102.00764@bozo> <3C116CC6.2030808@zytor.com>
In-Reply-To: <3C116CC6.2030808@zytor.com>
>
> The problem is that in the x86 architecture you don't have any reasonable
> way of addressing the physical address space, so you need to map it into
> the virtual address space. You end up with a shortage of virtual address
> space.
Isn't this still just an artifact of the default 1:3 kernel/user virtual
address space split? I've never tried it myself but isn't there a 2:2 patch
available that has the effect of moving the highmem boundary up?
>
> There is no way of fixing it.
All I know is that a streaming io app I was playing with showed a drastic
performance hit when the kernel was compiled with CONFIG_HIGHMEM. On W2K we
saw no slowdown with 2 or even 4GB of RAM so I think solutions must exist.
Marvin
next prev parent reply other threads:[~2001-12-08 1:49 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-12-07 13:06 highmem question Roy Sigurd Karlsbakk
2001-12-08 0:01 ` H. Peter Anvin
2001-12-08 1:30 ` Marvin Justice
2001-12-08 1:28 ` H. Peter Anvin
2001-12-08 1:53 ` Marvin Justice [this message]
2001-12-08 1:52 ` H. Peter Anvin
2001-12-08 1:54 ` Jens Axboe
2001-12-08 1:58 ` H. Peter Anvin
2001-12-08 2:02 ` Jens Axboe
2001-12-08 2:10 ` Marvin Justice
2001-12-08 2:08 ` H. Peter Anvin
2001-12-08 2:10 ` Jens Axboe
2001-12-08 3:43 ` war
2001-12-08 3:46 ` H. Peter Anvin
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