[systemd-devel] device enumeration by systemd user instances

[Greg KH]

On Thu, Jul 25, 2019 at 05:29:33PM +0200, Pawel Szewczyk wrote:
> On 7/17/19 23:14, Greg KH wrote:
> > 
> > 100ms seems like a really long time, what exactly is it doing during
> > that time?  Is the kernel spending too much time regenerating the
> > uevents?
> > 
> > How many devices are you talking about?  Any chance to see what really
> > is happening here by running perf to see where the hot-spots are?
> 
> There are ~80 devices being enumerated and 1ms per device still seem a 
> little too long. Note, that we are running this on arm architecture.
> 
> Maybe using perf or other tools to find out what exactly is taking this 
> time is a good idea (never used perf to be honest). For now just by 
> adding some verbose logs it seems that processing of each device 
> actually takes around 1ms.

Run perf and see what is going on, that seems like way too long per
device.

thanks,

greg k-h