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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: Thu, 3 May 2012 17:28:47 +0200	[thread overview]
Message-ID: <CAMSQXEEnvpBoq7m5hMTtYObj4FsMAtUbpEaiftZ1CDmF56LZAQ@mail.gmail.com> (raw)
In-Reply-To: <CAMSQXEG+O86t10AF5gN875RoEHkMcGFQE_-G6TdeYVc4NJoBLw@mail.gmail.com>

Hi,

>
> 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

I've changed some small things to the tty layer (see my other 3 RFC
patches I've send).
Performance increased with my loopback stress test:
- Old situation: average read call last for 50us, with peaks up to 230 us
- New situation: average read call still 50us, peak up to 60 us
- Write was stable in both situations: average of 90 us, peak up to 100 us

Only the very first read & write took extra time (128 us for read, 143
for write)
I'm still investigating that...

Feedback is very appreciated.

Regards,
Ivo Sieben

  reply	other threads:[~2012-05-03 15:28 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
2012-05-03 15:28                   ` Ivo Sieben [this message]
2012-05-05  0:32                     ` Greg KH
2012-04-19 11:19 ` Alan Cox
2012-04-19 15:42   ` Ivo Sieben

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