From: Ingo Molnar <mingo@elte.hu>
To: kus Kusche Klaus <kus@keba.com>
Cc: stern@rowland.harvard.edu, linux-usb-users@lists.sourceforge.net,
linux-kernel@vger.kernel.org
Subject: Re: 2.6.11, USB: High latency?
Date: Thu, 31 Mar 2005 13:30:24 +0200 [thread overview]
Message-ID: <20050331113024.GA27731@elte.hu> (raw)
In-Reply-To: <AAD6DA242BC63C488511C611BD51F3673231C5@MAILIT.keba.co.at>
* kus Kusche Klaus <kus@keba.com> wrote:
> I'm performing realtime latency tests (for details about the hardware
> and software, see my mail "[BUG] 2.6.11: Random SCSI/USB errors when
> reading from USB memory stick" erlier today).
>
> Even when the errors described in my previous mail does not occur,
> massive USB stick transfers cause latencies of 1 to 2 milliseconds,
> which is way too much for realtime control systems.
do these occur under PREEMPT_RT? If yes, do you get any useful trace if
you enable all the tracing options but keep wakeup-timing off:
# CONFIG_WAKEUP_TIMING is not set
CONFIG_PREEMPT_TRACE=y
CONFIG_CRITICAL_PREEMPT_TIMING=y
CONFIG_CRITICAL_IRQSOFF_TIMING=y
CONFIG_CRITICAL_TIMING=y
CONFIG_LATENCY_TIMING=y
CONFIG_LATENCY_TRACE=y
CONFIG_MCOUNT=y
this should catch any type of preempt-off section, irqs-off and
preempt_disable() alike. (unless the tracer has a bug.)
(WAKEUP_TIMING is useful and lightweight but if all other tracing
features are enabled it's a bit pointless, and a bit less accurate.)
Ingo
next prev parent reply other threads:[~2005-03-31 11:31 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-03-30 13:51 2.6.11, USB: High latency? kus Kusche Klaus
2005-03-30 15:55 ` Alan Stern
2005-03-30 21:28 ` Lee Revell
2005-03-31 11:30 ` Ingo Molnar [this message]
-- strict thread matches above, loose matches on Subject: below --
2005-03-30 22:57 David Brownell
2005-03-31 0:43 ` Lee Revell
2005-03-31 1:13 ` David Brownell
2005-03-31 1:21 ` Lee Revell
2005-03-31 1:32 ` David Brownell
2005-03-31 0:51 ` Lee Revell
2005-03-31 1:28 ` David Brownell
2005-03-31 1:32 ` Lee Revell
2005-03-31 1:40 ` David Brownell
2005-03-31 1:44 ` Lee Revell
2005-03-31 1:39 ` Lee Revell
2005-03-31 11:15 kus Kusche Klaus
2005-03-31 16:48 ` Alan Stern
2005-03-31 12:12 kus Kusche Klaus
2005-04-01 6:46 kus Kusche Klaus
2005-04-01 17:20 ` Alan Stern
2005-04-01 13:16 kus Kusche Klaus
2005-04-01 13:41 ` Ingo Molnar
2005-04-04 8:03 kus Kusche Klaus
2005-04-04 8:36 ` Ingo Molnar
2005-04-04 19:40 ` Alan Stern
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