* Re: scheduler question 2.6.16.x
2006-04-25 18:33 ` Nick Warne
@ 2006-04-25 18:51 ` Jens Axboe
2006-04-26 18:09 ` Andre Tomt
2006-04-27 21:39 ` Bill Davidsen
2 siblings, 0 replies; 7+ messages in thread
From: Jens Axboe @ 2006-04-25 18:51 UTC (permalink / raw)
To: Nick Warne; +Cc: linux-kernel
On Tue, Apr 25 2006, Nick Warne wrote:
> On Tuesday 25 April 2006 19:15, Jens Axboe wrote:
>
> > > But I can build both in... so I guess then the kernel decides what is
> > > the best to use? Or should it be so I am only allowed to select one
> > > or the other and allowing both is an oversight?
> >
> > See the option no more than two lines down from that, default io
> > scheduler. Also see Documentation/block/switching-sched.txt and/or
> > Documentation/kernel-parameters.txt (elevator=) section.
>
> Hi Jens,
>
> I haven't got the switching-sched.txt, although I found a
> sched-design.txt... but what I meant was if I select whatever
> default, do/can I still need to select either/or scheduler?
>
> i.e. why doesn't 'default selection option' only allow that scheduler
> to be selected?
I don't understand your question, but here's how it works. You can
select as many/few schedulers as you want. You can only set a scheduler
default, if it's compiled in (y, not m). If you don't select any
schedulers, noop is still selected and wil be the default.
Just try the options, you'll see how they work...
--
Jens Axboe
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: scheduler question 2.6.16.x
2006-04-25 18:33 ` Nick Warne
2006-04-25 18:51 ` Jens Axboe
@ 2006-04-26 18:09 ` Andre Tomt
2006-04-26 18:33 ` Nick Warne
2006-04-27 21:39 ` Bill Davidsen
2 siblings, 1 reply; 7+ messages in thread
From: Andre Tomt @ 2006-04-26 18:09 UTC (permalink / raw)
To: linux-kernel; +Cc: Nick Warne, Jens Axboe
Nick Warne wrote:
> On Tuesday 25 April 2006 19:15, Jens Axboe wrote:
>
>>> But I can build both in... so I guess then the kernel decides what is
>>> the best to use? Or should it be so I am only allowed to select one
>>> or the other and allowing both is an oversight?
>> See the option no more than two lines down from that, default io
>> scheduler. Also see Documentation/block/switching-sched.txt and/or
>> Documentation/kernel-parameters.txt (elevator=) section.
>
> Hi Jens,
>
> I haven't got the switching-sched.txt, although I found a sched-design.txt...
> but what I meant was if I select whatever default, do/can I still need to
> select either/or scheduler?
>
> i.e. why doesn't 'default selection option' only allow that scheduler to be
> selected?
That would be a artificial (and silly!) limit - the io-scheduler is
pluggable and selectable at boot, you can even change it at run time at
a per block device level.
See the elevator= boot option and /sys/block/<device>/queue/scheduler
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: scheduler question 2.6.16.x
2006-04-26 18:09 ` Andre Tomt
@ 2006-04-26 18:33 ` Nick Warne
0 siblings, 0 replies; 7+ messages in thread
From: Nick Warne @ 2006-04-26 18:33 UTC (permalink / raw)
To: Andre Tomt; +Cc: linux-kernel, Jens Axboe
On Wednesday 26 April 2006 19:09, Andre Tomt wrote:
> > i.e. why doesn't 'default selection option' only allow that scheduler to
> > be selected?
>
> That would be a artificial (and silly!) limit - the io-scheduler is
> pluggable and selectable at boot, you can even change it at run time at
> a per block device level.
>
> See the elevator= boot option and /sys/block/<device>/queue/scheduler
Ohh! I see. That is what I was sort of asking (but didn't know what
precisely to ask)... OK thanks, understand now.
Nick
--
"Person who say it cannot be done should not interrupt person doing it."
-Chinese Proverb
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: scheduler question 2.6.16.x
2006-04-25 18:33 ` Nick Warne
2006-04-25 18:51 ` Jens Axboe
2006-04-26 18:09 ` Andre Tomt
@ 2006-04-27 21:39 ` Bill Davidsen
2 siblings, 0 replies; 7+ messages in thread
From: Bill Davidsen @ 2006-04-27 21:39 UTC (permalink / raw)
To: Nick Warne; +Cc: linux-kernel
Nick Warne wrote:
> On Tuesday 25 April 2006 19:15, Jens Axboe wrote:
>
>>> But I can build both in... so I guess then the kernel decides what is
>>> the best to use? Or should it be so I am only allowed to select one
>>> or the other and allowing both is an oversight?
>> See the option no more than two lines down from that, default io
>> scheduler. Also see Documentation/block/switching-sched.txt and/or
>> Documentation/kernel-parameters.txt (elevator=) section.
>
> Hi Jens,
>
> I haven't got the switching-sched.txt, although I found a sched-design.txt...
> but what I meant was if I select whatever default, do/can I still need to
> select either/or scheduler?
>
> i.e. why doesn't 'default selection option' only allow that scheduler to be
> selected?
Not clear is you mean "allow that to the the only selection" which it
does, or "only allow that selection" which makes no sense, you can boot
using any compiled scheduler.
My configuration for beverage is set to "cask conditioned IPA" but I
have most of the "Microbrewed" selections for IPA, PA, Stout and Porter
compiled in. The "bland American and imported brews" section is
disabled, with "water" enabled as a module.
The preference is what you use by default, but not an irrevocable choice.
--
-bill davidsen (davidsen@tmr.com)
"The secret to procrastination is to put things off until the
last possible moment - but no longer" -me
^ permalink raw reply [flat|nested] 7+ messages in thread