[PATCH 2/5] vmbus: suppress uevents for hv_sock devices

[KY Srinivasan]

> -----Original Message-----
> From: Greg KH [mailto:gregkh at linuxfoundation.org]
> Sent: Sunday, September 10, 2017 1:10 AM
> To: KY Srinivasan <kys at microsoft.com>
> Cc: linux-kernel at vger.kernel.org; devel at linuxdriverproject.org;
> olaf at aepfle.de; apw at canonical.com; vkuznets at redhat.com;
> jasowang at redhat.com; leann.ogasawara at canonical.com;
> marcelo.cerri at canonical.com; Stephen Hemminger
> <sthemmin at microsoft.com>; Dexuan Cui <decui at microsoft.com>; Haiyang
> Zhang <haiyangz at microsoft.com>
> Subject: Re: [PATCH 2/5] vmbus: suppress uevents for hv_sock devices
> 
> On Sat, Sep 09, 2017 at 11:08:46PM -0700, kys at exchange.microsoft.com
> wrote:
> > From: Dexuan Cui <decui at microsoft.com>
> >
> > hv_sock driver is automatically loaded when an application creates an
> > AF_VSOCK socket, so we don't really need to trigger uevents to the user
> > space udevd.
> >
> > And hv_sock devices can appear and disappear frequency, e.g. 100 per
> > second, so triggering the udevents can cause a high cpu utilization of
> > udevd, e.g. 30% on a 2-cpu virtual machine. So let's suppress the
> > uevents to avoid this.
> 
> 100 per second for a struct device?  That's crazy, and the uevent is the
> least of your worries.  Please fix that, as it's not the correct way to
> use the driver model at all.
> 
> And really, why is uevent taking all that much cpu time anyway?  It
> _should_ be pretty fast, unless your distro is doing crazy things with
> it...
> 
> sorry, am not going to take this patch.

Greg,

This is not a real problem that needs fixing. The test automation triggered this condition.
I will drop this patch and send the rest.

Regards,

K. Y
> 
> greg k-h