From: Ivo Sieben <meltedpianoman@gmail.com>
To: Greg KH <gregkh@linuxfoundation.org>,
linux-serial@vger.kernel.org, Alan Cox <alan@linux.intel.com>,
RT <linux-rt-users@vger.kernel.org>
Subject: Re: Deterministic behavior for TTY serial
Date: Wed, 2 May 2012 14:39:07 +0200 [thread overview]
Message-ID: <CAMSQXEG+O86t10AF5gN875RoEHkMcGFQE_-G6TdeYVc4NJoBLw@mail.gmail.com> (raw)
In-Reply-To: <CAMSQXEHHOHeNYPJZT0b4s62T3uuNXSt9WucSrGOTfjXOU_guzg@mail.gmail.com>
Hi,
> 2012/5/2 Ivo Sieben <meltedpianoman@gmail.com>:
>> Hi,
>>
>> Indeed the lock is only taken for a very short time. So in most
>> situations it works fine, the lock is free, and can be taken quickly.
>> But when I stress my system (e.g. by continuously dumpling a lot of
>> text data to another serial terminal from the background), my high
>> priority task sometimes finds the lock is taken. In that case
>> additional lock handling comes in: priority inheritance, a context
>> switch to the background task that holds the lock, and a context
>> switch back after the lock is released again. This makes a normal read
>> that takes about 50us, to increase in execution time to 150us.
The PREEMPT_RT uses mutexes for "normal" spin locks that do not
disable interrupts...
I'll try to use raw spinlocks in this code section and for the tty flip buffer
See if that can solve my problem.
If you have other ideas... let me know!
Regards,
Ivo
--
To unsubscribe from this list: send the line "unsubscribe linux-serial" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
next prev parent reply other threads:[~2012-05-02 12:39 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-17 14:38 Deterministic behavior for TTY serial Ivo Sieben
2012-04-19 0:14 ` Greg KH
2012-04-19 15:37 ` Ivo Sieben
2012-04-19 15:46 ` Greg KH
2012-04-26 14:27 ` Ivo Sieben
2012-05-01 14:30 ` Ivo Sieben
2012-05-01 15:04 ` Alan Cox
[not found] ` <CAMSQXEHAyPOF6YghsYmqqyx+N0oMgn5E=znhgFyspMUnaH78ig@mail.gmail.com>
2012-05-02 8:38 ` Ivo Sieben
2012-05-02 12:39 ` Ivo Sieben [this message]
2012-05-03 15:28 ` Ivo Sieben
2012-05-05 0:32 ` Greg KH
2012-04-19 11:19 ` Alan Cox
2012-04-19 15:42 ` Ivo Sieben
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=CAMSQXEG+O86t10AF5gN875RoEHkMcGFQE_-G6TdeYVc4NJoBLw@mail.gmail.com \
--to=meltedpianoman@gmail.com \
--cc=alan@linux.intel.com \
--cc=gregkh@linuxfoundation.org \
--cc=linux-rt-users@vger.kernel.org \
--cc=linux-serial@vger.kernel.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.