From: Arnd Bergmann <arnd@arndb.de>
To: leoli@freescale.com
Cc: linuxppc-dev@ozlabs.org, linux-usb@vger.kernel.org,
linux-kernel@vger.kernel.org, dbrownell@users.sourceforge.net,
greg@kroah.com
Subject: Re: [PATCH] usb: add Freescale QE/CPM USB peripheral controller driver
Date: Fri, 29 Aug 2008 10:57:20 +0200 [thread overview]
Message-ID: <200808291057.20612.arnd@arndb.de> (raw)
In-Reply-To: <1220000265.30607.10.camel@Gundam>
On Friday 29 August 2008, Li Yang wrote:
>=20
> > Not a problem, but an observation: Most new code uses work queues inste=
ad
> > of tasklets these days, which gives you more predictable real time
> > latencies.
> > If you don't have a specific reason to prefer a tasklet, just use
> > a workqueue here.
>=20
> Is this truly a trend? =A0Work queue is more flexible but it has higher
> latency. =A0Why are work queues preferred?
Most drivers don't need the low irq to bottom half latency. As I said,
not a problem at all, just my observation. In 2.6.27, we have around
three times more new workqueue usages than new tasklet usages. My
feeling from doing reviews was that it would be closer to a factor
of ten, but I guess I was wrong in that.
Arnd <><
WARNING: multiple messages have this Message-ID (diff)
From: Arnd Bergmann <arnd@arndb.de>
To: leoli@freescale.com
Cc: linuxppc-dev@ozlabs.org, greg@kroah.com,
linux-usb@vger.kernel.org, dbrownell@users.sourceforge.net,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] usb: add Freescale QE/CPM USB peripheral controller driver
Date: Fri, 29 Aug 2008 10:57:20 +0200 [thread overview]
Message-ID: <200808291057.20612.arnd@arndb.de> (raw)
In-Reply-To: <1220000265.30607.10.camel@Gundam>
On Friday 29 August 2008, Li Yang wrote:
>
> > Not a problem, but an observation: Most new code uses work queues instead
> > of tasklets these days, which gives you more predictable real time
> > latencies.
> > If you don't have a specific reason to prefer a tasklet, just use
> > a workqueue here.
>
> Is this truly a trend? Work queue is more flexible but it has higher
> latency. Why are work queues preferred?
Most drivers don't need the low irq to bottom half latency. As I said,
not a problem at all, just my observation. In 2.6.27, we have around
three times more new workqueue usages than new tasklet usages. My
feeling from doing reviews was that it would be closer to a factor
of ten, but I guess I was wrong in that.
Arnd <><
next prev parent reply other threads:[~2008-08-29 8:57 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-08-28 9:43 [PATCH] usb: add Freescale QE/CPM USB peripheral controller driver Li Yang
2008-08-28 9:43 ` Li Yang
2008-08-28 15:04 ` Arnd Bergmann
2008-08-28 15:04 ` Arnd Bergmann
2008-08-28 17:22 ` Alan Stern
2008-08-28 17:22 ` Alan Stern
2008-08-28 17:53 ` Scott Wood
2008-08-28 17:53 ` Scott Wood
2008-08-28 20:16 ` Alan Stern
2008-08-28 20:16 ` Alan Stern
2008-08-28 22:27 ` Arnd Bergmann
2008-08-28 22:27 ` Arnd Bergmann
2008-08-29 16:05 ` Alan Stern
2008-08-29 16:05 ` Alan Stern
2008-08-29 16:29 ` Arnd Bergmann
2008-08-29 16:29 ` Arnd Bergmann
2008-08-29 17:19 ` Alan Stern
2008-08-29 17:19 ` Alan Stern
2008-08-29 17:38 ` Arnd Bergmann
2008-08-29 17:38 ` Arnd Bergmann
2008-08-29 21:22 ` Alan Stern
2008-08-29 21:22 ` Alan Stern
2008-09-24 20:15 ` David Brownell
2008-09-24 20:15 ` David Brownell
2008-08-29 8:57 ` Li Yang
2008-08-29 8:57 ` Li Yang
2008-08-29 8:57 ` Arnd Bergmann [this message]
2008-08-29 8:57 ` Arnd Bergmann
2008-09-24 20:10 ` David Brownell
2008-09-24 20:10 ` David Brownell
2008-08-28 16:39 ` Scott Wood
2008-08-28 16:39 ` Scott Wood
2008-08-29 9:35 ` Li Yang
2008-08-29 9:35 ` Li Yang
2008-09-01 13:52 ` Anton Vorontsov
2008-09-01 13:52 ` Anton Vorontsov
2008-09-02 7:08 ` Li Yang
2008-09-02 7:08 ` Li Yang
2008-09-01 16:34 ` Anton Vorontsov
2008-09-01 16:34 ` Anton Vorontsov
2008-09-01 17:11 ` Anton Vorontsov
2008-09-01 17:11 ` Anton Vorontsov
2008-09-02 7:35 ` Li Yang
2008-09-02 7:35 ` Li Yang
2008-09-02 7:57 ` Joakim Tjernlund
2008-09-02 7:57 ` Joakim Tjernlund
2008-09-02 8:12 ` [PATCH] usb: add Freescale QE/CPM USB peripheral controllerdriver Li Yang-R58472
2008-09-02 8:12 ` Li Yang-R58472
2008-09-02 8:15 ` Joakim Tjernlund
2008-09-02 8:15 ` Joakim Tjernlund
2008-09-24 20:28 ` David Brownell
2008-09-24 20:28 ` David Brownell
2008-09-24 21:30 ` Joakim Tjernlund
2008-09-24 21:42 ` David Brownell
2008-09-24 21:42 ` David Brownell
2008-09-24 20:26 ` David Brownell
2008-09-24 20:26 ` David Brownell
-- strict thread matches above, loose matches on Subject: below --
2008-08-06 7:16 [PATCH] usb: add Freescale QE/CPM USB peripheral controller driver Li Yang
2008-08-06 15:15 ` Anton Vorontsov
2008-08-06 15:47 ` Timur Tabi
2008-08-15 14:16 ` Anton Vorontsov
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