From: Lee Revell <rlrevell@joe-job.com>
To: John Hawkes <hawkes@sgi.com>
Cc: Zwane Mwaikambo <zwane@arm.linux.org.uk>,
"Luck, Tony" <tony.luck@intel.com>,
Tony Luck <tony.luck@gmail.com>, Andrew Morton <akpm@osdl.org>,
linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org,
Jack Steiner <steiner@sgi.com>, Keith Owens <kaos@sgi.com>,
Dimitri Sivanich <sivanich@sgi.com>
Subject: Re: [PATCH] ia64: disable preemption in udelay()
Date: Fri, 16 Dec 2005 03:19:11 +0000 [thread overview]
Message-ID: <1134703152.12086.231.camel@mindpipe> (raw)
In-Reply-To: <00b201c601e6$30c87ff0$d6069aa3@johnhaonw7lw1r>
On Thu, 2005-12-15 at 18:12 -0800, John Hawkes wrote:
> From: "Lee Revell" <rlrevell@joe-job.com>
> > There are 10 drivers that udelay(10000) or more and a TON that
> > udelay(1000). Turning those all into 1ms+ non preemptible sections will
> > be very bad.
>
> What about 100usec non-preemptible sections?
That will disappear into the noise, in normal usage these happen all the
time. 500usec non preemptible regions are rare (~1 hour to show up) and
1ms very rare (24 hours). My tests show that 300 usec or so is a good
place to draw the line if you don't want it to show up in latency tests.
Lee
WARNING: multiple messages have this Message-ID (diff)
From: Lee Revell <rlrevell@joe-job.com>
To: John Hawkes <hawkes@sgi.com>
Cc: Zwane Mwaikambo <zwane@arm.linux.org.uk>,
"Luck, Tony" <tony.luck@intel.com>,
Tony Luck <tony.luck@gmail.com>, Andrew Morton <akpm@osdl.org>,
linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org,
Jack Steiner <steiner@sgi.com>, Keith Owens <kaos@sgi.com>,
Dimitri Sivanich <sivanich@sgi.com>
Subject: Re: [PATCH] ia64: disable preemption in udelay()
Date: Thu, 15 Dec 2005 22:19:11 -0500 [thread overview]
Message-ID: <1134703152.12086.231.camel@mindpipe> (raw)
In-Reply-To: <00b201c601e6$30c87ff0$d6069aa3@johnhaonw7lw1r>
On Thu, 2005-12-15 at 18:12 -0800, John Hawkes wrote:
> From: "Lee Revell" <rlrevell@joe-job.com>
> > There are 10 drivers that udelay(10000) or more and a TON that
> > udelay(1000). Turning those all into 1ms+ non preemptible sections will
> > be very bad.
>
> What about 100usec non-preemptible sections?
That will disappear into the noise, in normal usage these happen all the
time. 500usec non preemptible regions are rare (~1 hour to show up) and
1ms very rare (24 hours). My tests show that 300 usec or so is a good
place to draw the line if you don't want it to show up in latency tests.
Lee
next prev parent reply other threads:[~2005-12-16 3:19 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-12-14 23:25 [PATCH] ia64: disable preemption in udelay() hawkes
2005-12-14 23:25 ` hawkes
2005-12-15 22:50 ` Luck, Tony
2005-12-15 22:50 ` Luck, Tony
2005-12-16 1:04 ` Luck, Tony
2005-12-16 1:04 ` Luck, Tony
2005-12-16 8:20 ` Christian Hildner
2005-12-16 8:20 ` Christian Hildner
2005-12-16 14:14 ` Alan Cox
2005-12-16 1:52 ` Zwane Mwaikambo
2005-12-16 1:52 ` Zwane Mwaikambo
2005-12-16 2:03 ` Lee Revell
2005-12-16 2:03 ` Lee Revell
2005-12-16 2:12 ` John Hawkes
2005-12-16 2:12 ` John Hawkes
2005-12-16 2:40 ` Zwane Mwaikambo
2005-12-16 2:40 ` Zwane Mwaikambo
2005-12-16 3:19 ` Lee Revell [this message]
2005-12-16 3:19 ` Lee Revell
2005-12-22 21:45 ` Bill Davidsen
2005-12-22 21:45 ` Bill Davidsen
2005-12-16 2:37 ` Zwane Mwaikambo
2005-12-16 2:37 ` Zwane Mwaikambo
2005-12-16 2:42 ` hawkes
2005-12-16 2:42 ` hawkes
2005-12-16 12:28 ` Robin Holt
2005-12-16 12:28 ` Robin Holt
2005-12-16 17:33 ` Luck, Tony
2005-12-16 17:33 ` Luck, Tony
2005-12-16 18:39 ` John Hawkes
2005-12-16 18:39 ` John Hawkes
2005-12-23 0:14 ` Keith Owens
2005-12-23 0:14 ` Keith Owens
2005-12-23 5:58 ` Zwane Mwaikambo
2005-12-23 6:03 ` Zwane Mwaikambo
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