On Sat, May 22, 2010 at 12:27:15PM +0200, Henrik Rydberg wrote: > Rafi Rubin wrote: > > -----BEGIN PGP SIGNED MESSAGE----- > > Hash: SHA1 > > > > On 05/22/10 03:42, Dmitry Torokhov wrote: > >> On Sat, May 22, 2010 at 03:06:07AM -0400, Rafi Rubin wrote: > >>> I'm playing with a project with a 2.6.29 kernel, and the userspace application > >>> seems to miss some events. Is there a particular fix that improved the handling? > >>> > >>> Also tried catting the dev to a file while testing, and the dump also is missing > >>> some events. > >>> > >> No "interesting" patches went into evdev for a few release now... > >> > >> Hm, could it be that event queue is overflowing before userspace gets a > >> chance to empty it. What kind of event rate are we talking here? > >> > > > > Quite possibly. It is a multitouch device and we know Henrik's been concerned > > with the load for a while. > > > > So to put some numbers behind his fears: > > > > 146668 hid events processed > > 24952 evdev events captured with a cat > > 30 seconds (give or take). > > > > This is for a mix of different numbers of fingers, but continuous use for those > > 30 seconds. And X was running and reading the dev node too. > > Others have experienced this too. Mika has a patch for this, increasing the > (kernel) evdev buffer quite a bit, from 64 to 256. I believe the reason it is > not sent upstream is because it increases the footprint by 3 Kb. Perhaps a > dynamic solution could work here. > Yes, if input devices could hint handlers about their "packet size" then evdev could size it's event queue accordingly. I'd say we need to keep about 8 packets worth of data (number is pulled right out of my behind ;) )... -- Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
