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From: yosi yarchi <yosi.yarchi@gmail.com>
To: linux-rt-users@vger.kernel.org
Subject: high latency introduced by hrtimer_interrupt
Date: Thu, 12 May 2022 06:39:23 +0300	[thread overview]
Message-ID: <7f336ac2-b664-452e-12e7-d29ccc53fbf6@gmail.com> (raw)
In-Reply-To: <87czrtorwp.ffs@nanos.tec.linutronix.de>

hi


I'm using linux-rt, 5.4.41, at91 sam9x35 (single core).


AFAIK, the hrtimer_interrupt must run at HW context, and could not be 
threaded.
On my system, hrtimer_interrupt processing takes ~100us in average, 
~40us in best case and ~200us in worst case. when adding the overhead of 
the re-scheduling that follow each interrupt, we get to worst case 
overhead of ~250us for the hrtimer_interrupt.
This worst case and the huge variance are too high for some of my 
threaded interrupts, which have to record timestamps of HW events with 
precision < 100us.

Digging in documentation and mailing lists, I didn't find any solution...


Any idea on how to overcome this problem?


With best regards
Yosi Yarchi


  reply	other threads:[~2022-05-12  3:39 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-29  4:54 Questions related to nano_sleep()/hrtimer manty kuma
2021-06-29 19:15 ` Chris Friesen
2021-07-08 13:29 ` Thomas Gleixner
2022-05-12  3:39   ` yosi yarchi [this message]
2022-05-12  5:13 high latency introduced by hrtimer_interrupt yosi yarchi
2022-05-25 11:50 ` Sebastian Andrzej Siewior

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