From: Henrik Rydberg <rydberg@euromail.se>
To: Rafi Rubin <rafi@seas.upenn.edu>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>,
linux-input <linux-input@vger.kernel.org>,
Jiri Kosina <jkosina@suse.cz>,
Mika Kuoppala <mika.kuoppala@nokia.com>
Subject: Re: Lost events in older kernels
Date: Sat, 22 May 2010 12:27:15 +0200 [thread overview]
Message-ID: <4BF7B183.2050801@euromail.se> (raw)
In-Reply-To: <4BF7A247.5090307@seas.upenn.edu>
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.
Henrik
next prev parent reply other threads:[~2010-05-22 10:31 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-22 7:06 Lost events in older kernels Rafi Rubin
2010-05-22 7:42 ` Dmitry Torokhov
2010-05-22 9:22 ` Rafi Rubin
2010-05-22 10:27 ` Henrik Rydberg [this message]
2010-05-22 20:12 ` Dmitry Torokhov
2010-05-22 20:57 ` Henrik Rydberg
2010-05-22 21:08 ` Dmitry Torokhov
2010-05-22 21:26 ` Henrik Rydberg
2010-05-23 2:10 ` Rafi Rubin
2010-05-23 2:24 ` Dmitry Torokhov
2010-05-23 8:44 ` Henrik Rydberg
2010-05-24 17:48 ` Dmitry Torokhov
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