Re: USB interrupt times

[Jiri Kosina <jkosina@xxxxxxx>]

On Tue, 14 Aug 2012, Russell King wrote:

> > Actually, Henrik (added to CC) has been doing some latency improvements 
> > both for input core in general, and for HID devices as well lately. I 
> > still have his patchset in my to-review queue, as I have just came back 
> > from offline vacation, but the patch below definitely can't hurt and 
> > should significantly lower the time spent in handling the irq for hid 
> > device in common situation (i.e. noone listening for debugfs events).
> > 
> > Could you please measure how much it helps on your system?
> 
> Ok, it looks like it's changed the maximum USB interrupt execution
> time from around 364us to 255us.
> 
> If I also do a similar trick with the debug code in hid_input_report()
> then I get down to 212us - iow, something like the patch below.

Are you testing with kernel that contains b94e3c94aae04 already? That 
should cover that case.

-- 
Jiri Kosina
SUSE Labs
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