From: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
To: Philippe Gerum <rpm@xenomai.org>
Cc: "xenomai@xenomai.org" <xenomai@xenomai.org>
Subject: Re: [Xenomai-help] Interrupt latency greater than 250ms
Date: Tue, 01 May 2012 18:26:42 +0200 [thread overview]
Message-ID: <4FA00EC2.5080806@domain.hid> (raw)
In-Reply-To: <4F9925E3.9020702@domain.hid>
On 04/26/2012 12:39 PM, Philippe Gerum wrote:
> On 04/12/2012 05:57 PM, Philippe Gerum wrote:
>> On 04/12/2012 05:45 PM, Michael Pustylnik wrote:
>>> The code masking the interrupt in IPIC (call for
>>> ipipe_pre_cascade_noeoi()) initially showed up in the patch you
>>> recommended (see your email attached).
>>>
>>> Later on it was integrated in Xenomai commit
>>> "9a5e42df8bccc59620c08caeb4b9fe92dbf94a1b".
>>>
>>> As shown in the trail below, it keeps interrupts all the time until the
>>> scheduler returns, thus breaking real-time responsiveness.
>>>
>>> A solution to this is probably to remove calling
>>> ipipe_pre_cascade_noeoi() and let the cascading handler mask the
>>> interrupt. Am I missing something? Do you think it is safe to use this
>>> solution?
>>
>> No, as interrupts could be re-enabled before invoking the handler, you
>> would get an IRQ storm.
>>
>> The solution is to rework the cascaded IRQ handling in the generic
>> pipeline core, so that all decoded IRQs are acked/masked, then the
>> multiplex IRQ unmasked, then all the decoded IRQ handlers fired when
>> syncing the relevant pipeline stage.
>>
>> A fix for this will follow when enough testing will have been done on
>> arm and ppc, to check whether that logic does not raise other issue.
>>
>
> This is the patch series fixing the issue in the newest pipeline "core"
> implementation, currently for kernel 3.2. Something along these lines would work for
> earlier kernels as well.
>
> http://git.denx.de/?p=ipipe-2.6.git;a=commit;h=0a9a7b4e4ce9f4196a574471ad58f4389820c438
> http://git.denx.de/?p=ipipe-2.6.git;a=commit;h=f2ca3c2baf58bf43f4c00fb05b91b16da9fd77f2
> http://git.denx.de/?p=ipipe-2.6.git;a=commit;h=a4b909ccf80c5afa132aa7a9ccf0022cb8a6e6f2
> http://git.denx.de/?p=ipipe-2.6.git;a=commit;h=b47bc773ff07ce886aaf490921ac59e98ed9575a
I have done a backport of this change for a pre ipipe-core (ARM) I-pipe. The diff is here:
http://git.xenomai.org/?p=ipipe-gch.git;a=commitdiff;h=81bfc05c4716b76e79f5e486baf4c52015a3b92c;hp=7d31a77f62acb57eb83409c8f514d0f2dacf7fe5
--
Gilles.
prev parent reply other threads:[~2012-05-01 16:26 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-28 15:53 [Xenomai-help] Interrupt latency greater than 250ms. Question Makarand Pradhan
2012-03-28 16:17 ` Philippe Gerum
2012-03-28 18:23 ` Makarand Pradhan
2012-04-02 15:04 ` Philippe Gerum
2012-04-04 16:59 ` Makarand Pradhan
2012-04-12 15:45 ` [Xenomai-help] Interrupt latency greater than 250ms Michael Pustylnik
2012-04-12 15:57 ` Philippe Gerum
2012-04-26 10:39 ` Philippe Gerum
2012-05-01 16:26 ` Gilles Chanteperdrix [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4FA00EC2.5080806@domain.hid \
--to=gilles.chanteperdrix@xenomai.org \
--cc=rpm@xenomai.org \
--cc=xenomai@xenomai.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.