Block IO throttling disabled in distros

Block IO throttling disabled in distros

[Haefliger, Juerg]

Hi,

Both RHEL6 and Ubuntu 10.10 have block IO throttling disabled in their kernels. Does anybody know why that is? Are there performance or stability issues with the throttling controller or does it somehow negatively interfere with the rest of the kernel and/or system?

Thanks
...Juerg

Re: Block IO throttling disabled in distros

[Vivek Goyal]

On Mon, Feb 07, 2011 at 03:33:38PM +0000, Haefliger, Juerg wrote:
> Hi,
> 
> Both RHEL6 and Ubuntu 10.10 have block IO throttling disabled in their kernels. Does anybody know why that is? Are there performance or stability issues with the throttling controller or does it somehow negatively interfere with the rest of the kernel and/or system?

Block IO throttling support was not even upstream at that time hence
you don't see it. 

I have not heard about any stability issues so far. Of course more testing
will reveal that.

The only thing I have thinking is that should we limit the number of bios
queued per IO context on the device. Currently there is no such limit
and one can queue up as many bios as one want to.

Thanks
Vivek

RE: Block IO throttling disabled in distros

[Haefliger, Juerg]

> On Mon, Feb 07, 2011 at 03:33:38PM +0000, Haefliger, Juerg wrote:
> > Hi,
> >
> > Both RHEL6 and Ubuntu 10.10 have block IO throttling disabled in
> their kernels. Does anybody know why that is? Are there performance or
> stability issues with the throttling controller or does it somehow
> negatively interfere with the rest of the kernel and/or system?
> 
> Block IO throttling support was not even upstream at that time hence
> you don't see it.

Duh! I thought I checked that the code was there but just not enabled. I just double-checked and sure enough block IO throttling is not in the RHEL6 kernel source. Sorry for the noise.

Thanks
...Juerg


> I have not heard about any stability issues so far. Of course more
> testing will reveal that.
> 
> The only thing I have thinking is that should we limit the number of
> bios queued per IO context on the device. Currently there is no such limit
> and one can queue up as many bios as one want to.
>
>
> Thanks
> Vivek

Re: Block IO throttling disabled in distros

[Tim Gardner]

On 02/08/2011 12:24 AM, Haefliger, Juerg wrote:
>> On Mon, Feb 07, 2011 at 03:33:38PM +0000, Haefliger, Juerg wrote:
>>> Hi,
>>>
>>> Both RHEL6 and Ubuntu 10.10 have block IO throttling disabled in
>> their kernels. Does anybody know why that is? Are there performance or
>> stability issues with the throttling controller or does it somehow
>> negatively interfere with the rest of the kernel and/or system?
>>
>> Block IO throttling support was not even upstream at that time hence
>> you don't see it.
>
> Duh! I thought I checked that the code was there but just not enabled. I just double-checked and sure enough block IO throttling is not in the RHEL6 kernel source. Sorry for the noise.
>
> Thanks
> ...Juerg
>
>
>> I have not heard about any stability issues so far. Of course more
>> testing will reveal that.
>>
>> The only thing I have thinking is that should we limit the number of
>> bios queued per IO context on the device. Currently there is no such limit
>> and one can queue up as many bios as one want to.
>>
>>
>> Thanks
>> Vivek
> --

CONFIG_BLK_DEV_THROTTLING=y in what will be Ubuntu 11.04

rtg
-- 
Tim Gardner tim.gardner@canonical.com