Re: [announce] mdevd- - a mdev-compatible uevent manager

From: Laurent Bercot <>
Date: Mon, 15 Jan 2018 16:52:06 +0000

>And to answer your question, about what could cause such a burst of
>events, this time I have an easy answer: mdevd-coldplug !

  Yes, I forgot to mention this.

  The kernel-generated events seem to be significantly heavier than the
mdev-style synthetic ones. The DEVPATH is the full path without
symlinks, which is usually pretty long, and there are also a bunch
of misc variables with every event. It's very common for a kernel-
generated event to reach 250 bytes, which means a 64kB buffer can
only hold 256 events, and probably less because some events are
easily 300 bytes long; so I tripled the buffer size.

  If it's not enough for a run-of-the-mill desktop PC, I should
increase it again. 1 MB sounds really excessive though: it means
it would be able to hold 3000 to 4000 events. Can you run
mdevd-coldplug with a dry-run mdevd to count the number of events,
you're getting and their approximate size? A nice trick to trace
events is to add the following line at the top of your mdev.conf file:

-.* 0:0 0600 ! _at_env

which will send a bunch of lines to your catch-all logger. :)

  Thanks for testing!

Received on Mon Jan 15 2018 - 16:52:06 UTC

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