From: Fabrice Bellard <fabrice@bellard.org>
To: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] Re: [RFC][PATCH] x86: CS limit checks
Date: Thu, 17 Jul 2008 21:29:24 +0200 [thread overview]
Message-ID: <487F9D94.5080507@bellard.org> (raw)
In-Reply-To: <487F73AE.50509@siemens.com>
[...]
> And then there is the open question how much performance can be gained
> with compile-time optimization for those guests who do use segmentation.
The goal is to optimize the cases where segmentation is not used ! It is
just an extension of the existing "HF_ADDSEG" optimization.
> The worst case is very roughly about 50% slowdown right now (/w vs. w/o
> -seg-checks). As answered privately, some -no-seg-checks switch could
> remain a useful optimization.
Not sure. I believe most recent OSes (i.e. those where speed really
matters) have segment registers loaded so that no runtime checks are
necessary.
Fabrice.
next prev parent reply other threads:[~2008-07-17 19:29 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-07-17 11:57 [Qemu-devel] [RFC][PATCH] x86: CS limit checks Jan Kiszka
2008-07-17 12:17 ` Paul Brook
2008-07-17 13:14 ` Jan Kiszka
2008-07-17 13:37 ` Paul Brook
2008-07-17 16:10 ` Jan Kiszka
2008-07-17 17:45 ` Paul Brook
2008-07-17 19:24 ` Fabrice Bellard
2008-07-17 21:30 ` [Qemu-devel] " Jan Kiszka
2008-07-17 14:06 ` [Qemu-devel] " Fabrice Bellard
2008-07-17 16:30 ` [Qemu-devel] " Jan Kiszka
2008-07-17 19:29 ` Fabrice Bellard [this message]
2008-07-17 21:25 ` Jan Kiszka
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