From: Avi Kivity <avi@redhat.com>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Sasha Levin <levinsasha928@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>,
Pekka Enberg <penberg@kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [patch 0/3] kvm tool: Serial emulation overhaul
Date: Mon, 12 Dec 2011 20:21:46 +0200 [thread overview]
Message-ID: <4EE6463A.2010007@redhat.com> (raw)
In-Reply-To: <20111212110236.755eda81@pyramind.ukuu.org.uk>
On 12/12/2011 01:02 PM, Alan Cox wrote:
> > > You can emulate a chip with a 64byte or so FIFO. You can do I/O cycle
> > > prediction in the kernel part and you can use the empty bit as a clue
> > > (which is what most serial<->ethernet widgetry does).
> >
> > The performance problems here aren't the same performance problems you
> > have on real hardware. The problem here is that it costs 40k cycles for
> > the guest to access the emulated chip.
>
> How much of that 40K cycles is bouncing back and forth into emulation
> layers and how much of it is the kernel trap ?
>
30K of those cycles are only in Sasha's mind, the real figure is 10K
(and likely lower with newer hardware).
--
error compiling committee.c: too many arguments to function
next prev parent reply other threads:[~2011-12-12 18:22 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-10 13:27 [patch 0/3] kvm tool: Serial emulation overhaul Thomas Gleixner
2011-12-10 13:27 ` [patch 1/3] kvm tool: serial: Cleanup coding style Thomas Gleixner
2011-12-10 13:27 ` [patch 3/3] kvm tool: serial: Fix interrupt handling Thomas Gleixner
2011-12-10 13:27 ` [patch 2/3] kvm tool: serial: Simplify switch cases Thomas Gleixner
2011-12-10 15:17 ` [patch 0/3] kvm tool: Serial emulation overhaul Pekka Enberg
2011-12-10 20:51 ` Thomas Gleixner
2011-12-11 8:15 ` Pekka Enberg
2011-12-11 10:30 ` Ingo Molnar
2011-12-11 10:46 ` Ingo Molnar
2011-12-11 14:04 ` Thomas Gleixner
2011-12-11 15:53 ` Ingo Molnar
2011-12-12 5:30 ` Sasha Levin
2011-12-12 11:12 ` Ingo Molnar
2011-12-12 11:20 ` Alan Cox
2011-12-12 17:20 ` Ingo Molnar
2011-12-12 18:16 ` Avi Kivity
2011-12-12 18:16 ` Avi Kivity
2011-12-12 21:36 ` Alan Cox
2011-12-13 10:32 ` Avi Kivity
2011-12-12 11:23 ` Cyrill Gorcunov
2011-12-12 17:40 ` Sasha Levin
2011-12-12 17:45 ` Ingo Molnar
2011-12-12 9:42 ` Thomas Gleixner
2011-12-12 11:19 ` Pekka Enberg
2011-12-12 17:20 ` Ingo Molnar
2011-12-12 18:40 ` Pekka Enberg
2011-12-12 19:14 ` Pekka Enberg
2011-12-12 19:21 ` Ingo Molnar
2011-12-13 0:59 ` Thomas Gleixner
2011-12-13 7:03 ` Pekka Enberg
2011-12-13 11:05 ` Alan Cox
2011-12-13 10:58 ` Avi Kivity
2011-12-13 13:52 ` Thomas Gleixner
2011-12-13 14:23 ` Avi Kivity
2011-12-13 14:30 ` Sasha Levin
2011-12-13 14:51 ` Thomas Gleixner
2011-12-13 14:58 ` Avi Kivity
2011-12-12 21:03 ` James Courtier-Dutton
2011-12-12 18:19 ` Avi Kivity
2011-12-12 18:31 ` Pekka Enberg
2011-12-13 10:33 ` Avi Kivity
2011-12-12 10:27 ` Alan Cox
2011-12-12 10:59 ` Sasha Levin
2011-12-12 11:02 ` Alan Cox
2011-12-12 18:21 ` Avi Kivity [this message]
2011-12-12 17:21 ` Ingo Molnar
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