On Sat, May 22, 2010 at 10:10:42PM -0400, Rafi Rubin wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > On 05/22/10 16:12, Dmitry Torokhov wrote: > > 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 ;) )... > > Um, turns out I missed input_init_abs_bypass(void) in my backport, and for some > reason get a bit of corruption ;) > > Sorry for the false alarm. > > As for buffering, strategies, if we have a rate of reports from the device, I'd > vote for sizing the buffer based on time. > > Does the code make sure we don't drop parts of a report? > No, it does not. Evdev has no idea about the size of a report. -- 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
