From: "Heike C. Zimmerer" <nospam05q1@gmx.net>
To: qemu-devel@nongnu.org
Subject: [Qemu-devel] Re: [patch] option -no-tsc for i386 with speedstep
Date: Mon, 25 Apr 2005 17:44:18 +0200 [thread overview]
Message-ID: <d4j3hh$pum$1@sea.gmane.org> (raw)
In-Reply-To: 20050425111532.GA2554@dizzy.ath.cx
Massimo Dal Zotto <dz@debian.org> writes:
> When qemu runs on an i386 cpu with speedstep enabled the clock of the
> guest os is not in sync with the clock on the host os because the
> vm_timer used for irq 0 generates interrupts at wrong rate when
> the host cpu frequency changes.
>
> The following patch fixes the problem by adding a new option -no-tsc for
> the i386 architecture which can be used to disable rdtsc when running on
> a cpu with speedstep enabled.
Unfortunately this patch, effectively replacing a single assembly
instruction by a gettimeofday() call, slows some operations down to a
degree that makes a WinXP guest on GNU/Linux host nearly unusable at
network and file system operations (at least here).
- Heike
next prev parent reply other threads:[~2005-04-25 15:56 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-04-25 11:15 [Qemu-devel] [patch] option -no-tsc for i386 with speedstep Massimo Dal Zotto
2005-04-25 15:44 ` Heike C. Zimmerer [this message]
2005-04-25 17:07 ` Jim C. Brown
2005-04-25 17:28 ` Paul Brook
2005-04-25 17:44 ` Massimo Dal Zotto
2005-04-25 17:47 ` [Qemu-devel] " Heike C. Zimmerer
2005-04-25 18:58 ` [Qemu-devel] " Fabrice Bellard
2005-04-25 20:17 ` Massimo Dal Zotto
2005-04-25 20:24 ` Jonas Maebe
2005-04-25 20:38 ` Filip Navara
2005-04-25 21:03 ` Lionel Ulmer
2005-04-25 22:45 ` Taras Glek
2005-04-25 21:46 ` [Qemu-devel] [patch] option -no-tsc for i386 with speedstep (solved) Massimo Dal Zotto
2005-04-26 6:50 ` Jonas Maebe
2005-04-26 3:03 ` [Qemu-devel] [patch] option -no-tsc for i386 with speedstep Kyle Hayes
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