Re: USB interrupt times

On Tue, 14 Aug 2012, Russell King wrote:

quoted

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