Re: USB interrupt times

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On Wed, Aug 15, 2012 at 11:02:37AM +0200, Jiri Kosina wrote:
> 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.

No - the kernel I'm dealing with is unfortunately based upon v3.5.0-rc5
with many other patches on top (which add support for this platform.)
However, I'll pick that commit into this tree.

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:
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