From: Matthias Meier <matthias.j.meier@gmx.net>
To: linux-rt-users@vger.kernel.org
Subject: Long max latencies on Wandbaord / Freescale i.MX6
Date: Fri, 2 Oct 2015 08:48:00 +0200 [thread overview]
Message-ID: <560E28A0.4010203@gmx.net> (raw)
In-Reply-To: <alpine.DEB.2.11.1509300909240.4500@nanos>
Comming to the end of my CONFIG_PROVE_LOCKING / "max latency" story:
It is not a spurious interrupt...
The source of problem is the WiFi driver (brcmfmac via SDIO) which
produces up to 6k interrupts per second, which when
CONFIG_PROOVE_LOCKING is enabled, results sporadically in very long
latencies (up to 10ms). (Possible because pending interrupts were queued).
Further after exactly 1600001 interrupts, the kernel disables this mmc
interrupt with "__report_bad_irq"
(The mmc driver is not only used for SD-cards but also for the SDIO
attached devices.)
Or with other words: never use (this) WiFi on a realtime system...
Regards and sorry for the noise I produced on this list
Matthias
next prev parent reply other threads:[~2015-10-02 6:48 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-26 9:38 Long max latencies on Wandbaord / Freescale i.MX6 Matthias Meier
2015-09-26 14:16 ` Joe Korty
2015-09-26 14:52 ` Matthias Meier
2015-09-27 11:49 ` Thomas Gleixner
2015-09-29 6:30 ` Matthias Meier
2015-09-29 7:04 ` Re[2]: " Matthias Klein
2015-09-30 7:11 ` Thomas Gleixner
2015-10-01 8:08 ` Matthias Meier
2015-10-02 6:48 ` Matthias Meier [this message]
2015-10-02 7:40 ` Mats Karrman
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