From: Gerd Hoffmann <kraxel@redhat.com>
To: Michael Tokarev <mjt@tls.msk.ru>
Cc: qemu-devel <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] udev 42-qemu-usb.rules considered harmful?
Date: Wed, 17 Oct 2012 10:56:19 +0200 [thread overview]
Message-ID: <507E72B3.2010003@redhat.com> (raw)
In-Reply-To: <507E6F32.4070009@msgid.tls.msk.ru>
On 10/17/12 10:41, Michael Tokarev wrote:
> Hello.
>
> I noticed that "some" versions of linux guests shows quite
What is "some"?
> As far as I can see, this rule is to reduce polling interrupt
> frequency, but apparently it does not help: any usb device
> connected to guest, and the host CPU usage rises anyway, with
> or without this rule.
No, it is for suspending the usb bus, so qemu stops doing 1000 wakeups
per second when the usb tablet is idle. Works only in case all devices
on the usb bus support it, but for the typical usb use case (-usbdevice
tablet for the abs ptr) this is the case.
> Now the question: should we remove this rule?
No. We should fix whatever is broken.
> Why it is needed
> to start with?
See above.
cheers,
Gerd
next prev parent reply other threads:[~2012-10-17 8:56 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-17 8:41 [Qemu-devel] udev 42-qemu-usb.rules considered harmful? Michael Tokarev
2012-10-17 8:56 ` Gerd Hoffmann [this message]
2012-10-17 9:15 ` Michael Tokarev
2012-10-17 9:21 ` Michael Tokarev
2012-10-17 10:58 ` Gerd Hoffmann
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