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From: Ulrich Drepper <drepper@gmail.com>
To: Brian Gerst <bgerst@didntduck.org>
Cc: Arjan van de Ven <arjan@infradead.org>,
	Tymm Twillman <ttwillman@penguincomputing.com>,
	linux-kernel@vger.kernel.org
Subject: Re: 2.4, 2.6, i686/athlon and LDT's
Date: Mon, 27 Dec 2004 15:44:07 -0800	[thread overview]
Message-ID: <a36005b5041227154457b24773@mail.gmail.com> (raw)
In-Reply-To: <41D076D9.30404@didntduck.org>

On Mon, 27 Dec 2004 15:55:53 -0500, Brian Gerst <bgerst@didntduck.org> wrote:
> Using the LDT isn't inherently slower, since the cpu caches the segment
> descriptor regardless of if it came from the GDT or LDT.

Not using LDT's on 2.4 kernel other than RHEL3's means to have a
different ABI.  This is the /lib/libpthread.so.0 RH is shipping which
simply cannot be used in some/many situations since there is no
"thread register".  This means the programmer is not able to select
size and/or location of the stacks.  Interfaces like
pthread_attr_setstack() simply won't work at all.

So, do't confuse people with "does anyone have comparison information
w/threads using
LDT's and without (performance, protection, etc)?".  That's comparing
apples and oranges.

      parent reply	other threads:[~2004-12-27 23:44 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-12-27 19:46 2.4, 2.6, i686/athlon and LDT's Tymm Twillman
2004-12-27 20:22 ` Arjan van de Ven
2004-12-27 20:55   ` Brian Gerst
2004-12-27 21:29     ` Arjan van de Ven
2004-12-27 23:44     ` Ulrich Drepper [this message]

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