[Qemu-devel] slow speed for virtio-scsi since qemu 2.2

[Qemu-devel] slow speed for virtio-scsi since qemu 2.2

[Stefan Priebe]

Hi,

while i get a constant random 4k i/o write speed of 20.000 iops with 
qemu 2.1.0 or 2.1.3. I get jumping speeds with qemu 2.2 (jumping between 
500 iops and 15.000 iop/s).

If i use virtio instead of virtio-scsi speed is the same between 2.2 and 
2.1.

Is there a known regression?

Greets,
Stefan

Re: [Qemu-devel] slow speed for virtio-scsi since qemu 2.2

[Alexandre DERUMIER]

H Stefan,

only for write ? or also read ?

I'll try to reproduce on my test cluster.


----- Mail original -----
De: "Stefan Priebe" <s.priebe@profihost.ag>
À: "qemu-devel" <qemu-devel@nongnu.org>
Envoyé: Dimanche 15 Février 2015 19:46:12
Objet: [Qemu-devel] slow speed for virtio-scsi since qemu 2.2

Hi, 

while i get a constant random 4k i/o write speed of 20.000 iops with 
qemu 2.1.0 or 2.1.3. I get jumping speeds with qemu 2.2 (jumping between 
500 iops and 15.000 iop/s). 

If i use virtio instead of virtio-scsi speed is the same between 2.2 and 
2.1. 

Is there a known regression? 

Greets, 
Stefan 

Re: [Qemu-devel] slow speed for virtio-scsi since qemu 2.2

[Paolo Bonzini]

On 15/02/2015 19:46, Stefan Priebe wrote:
> 
> while i get a constant random 4k i/o write speed of 20.000 iops with
> qemu 2.1.0 or 2.1.3. I get jumping speeds with qemu 2.2 (jumping between
> 500 iops and 15.000 iop/s).
> 
> If i use virtio instead of virtio-scsi speed is the same between 2.2 and
> 2.1.

http://wiki.qemu.org/Contribute/ReportABug

What is your command line?

Paolo

Re: [Qemu-devel] slow speed for virtio-scsi since qemu 2.2

[Stefan Priebe - Profihost AG]

Hi,

Am 16.02.2015 um 13:24 schrieb Paolo Bonzini:
> 
> 
> On 15/02/2015 19:46, Stefan Priebe wrote:
>>
>> while i get a constant random 4k i/o write speed of 20.000 iops with
>> qemu 2.1.0 or 2.1.3. I get jumping speeds with qemu 2.2 (jumping between
>> 500 iops and 15.000 iop/s).
>>
>> If i use virtio instead of virtio-scsi speed is the same between 2.2 and
>> 2.1.
> 
> http://wiki.qemu.org/Contribute/ReportABug
> 
> What is your command line?
> 
> Paolo
> 

Could it be that this is a results of compiling qemu with --enable-debug
to get debugging symbols?

Stefan

Re: [Qemu-devel] slow speed for virtio-scsi since qemu 2.2

[Paolo Bonzini]

On 16/02/2015 15:43, Stefan Priebe - Profihost AG wrote:
> Hi,
> 
> Am 16.02.2015 um 13:24 schrieb Paolo Bonzini:
>>
>>
>> On 15/02/2015 19:46, Stefan Priebe wrote:
>>>
>>> while i get a constant random 4k i/o write speed of 20.000 iops with
>>> qemu 2.1.0 or 2.1.3. I get jumping speeds with qemu 2.2 (jumping between
>>> 500 iops and 15.000 iop/s).
>>>
>>> If i use virtio instead of virtio-scsi speed is the same between 2.2 and
>>> 2.1.
>>
>> http://wiki.qemu.org/Contribute/ReportABug
>>
>> What is your command line?
> 
> Could it be that this is a results of compiling qemu with --enable-debug
> to get debugging symbols?

Yes.

Paolo

Re: [Qemu-devel] slow speed for virtio-scsi since qemu 2.2

[Stefan Priebe - Profihost AG]

Hi,
Am 16.02.2015 um 15:44 schrieb Paolo Bonzini:
> 
> 
> On 16/02/2015 15:43, Stefan Priebe - Profihost AG wrote:
>> Hi,
>>
>> Am 16.02.2015 um 13:24 schrieb Paolo Bonzini:
>>>
>>>
>>> On 15/02/2015 19:46, Stefan Priebe wrote:
>>>>
>>>> while i get a constant random 4k i/o write speed of 20.000 iops with
>>>> qemu 2.1.0 or 2.1.3. I get jumping speeds with qemu 2.2 (jumping between
>>>> 500 iops and 15.000 iop/s).
>>>>
>>>> If i use virtio instead of virtio-scsi speed is the same between 2.2 and
>>>> 2.1.
>>>
>>> http://wiki.qemu.org/Contribute/ReportABug
>>>
>>> What is your command line?
>>
>> Could it be that this is a results of compiling qemu with --enable-debug
>> to get debugging symbols?
> 
> Yes.

*urg* my fault - sorry. Is there a way to get debugging symbols without
using enable-debug / getting slower performance?

Greets,
Stefan

Re: [Qemu-devel] slow speed for virtio-scsi since qemu 2.2

[Paolo Bonzini]

On 16/02/2015 15:47, Stefan Priebe - Profihost AG wrote:
>>> >>
>>> >> Could it be that this is a results of compiling qemu with --enable-debug
>>> >> to get debugging symbols?
>> > 
>> > Yes.
> *urg* my fault - sorry. Is there a way to get debugging symbols without
> using enable-debug / getting slower performance?

Yes, just do nothing ("--enable-debug-info" is the default;
"--enable-debug" enables debug info _and_ turns off optimization).

Paolo

Re: [Qemu-devel] slow speed for virtio-scsi since qemu 2.2

[Stefan Priebe - Profihost AG]

> Am 16.02.2015 um 15:49 schrieb Paolo Bonzini <pbonzini@redhat.com>:
> 
> 
> 
> On 16/02/2015 15:47, Stefan Priebe - Profihost AG wrote:
>>>>>> 
>>>>>> Could it be that this is a results of compiling qemu with --enable-debug
>>>>>> to get debugging symbols?
>>>> 
>>>> Yes.
>> *urg* my fault - sorry. Is there a way to get debugging symbols without
>> using enable-debug / getting slower performance?
> 
> Yes, just do nothing ("--enable-debug-info" is the default;
> "--enable-debug" enables debug info _and_ turns off optimization).

If I do not enable-debug dh_strip does not extract any debugging symbols.

Stefan 

> 
> Paolo

Re: [Qemu-devel] slow speed for virtio-scsi since qemu 2.2

[Paolo Bonzini]

On 16/02/2015 16:41, Stefan Priebe - Profihost AG wrote:
>> > Yes, just do nothing ("--enable-debug-info" is the default;
>> > "--enable-debug" enables debug info _and_ turns off optimization).
> If I do not enable-debug dh_strip does not extract any debugging symbols.

Then you need --disable-strip too.

Paolo

Re: [Qemu-devel] slow speed for virtio-scsi since qemu 2.2

[Stefan Priebe]

Am 16.02.2015 um 16:49 schrieb Paolo Bonzini:
>
>
> On 16/02/2015 16:41, Stefan Priebe - Profihost AG wrote:
>>>> Yes, just do nothing ("--enable-debug-info" is the default;
>>>> "--enable-debug" enables debug info _and_ turns off optimization).
>> If I do not enable-debug dh_strip does not extract any debugging symbols.
>
> Then you need --disable-strip too.

Thanks!

Stefan

>
> Paolo
>

Re: [Qemu-devel] slow speed for virtio-scsi since qemu 2.2

[Andreas Färber]

Am 16.02.2015 um 16:41 schrieb Stefan Priebe - Profihost AG:
>> Am 16.02.2015 um 15:49 schrieb Paolo Bonzini <pbonzini@redhat.com>:
>>
>>
>>
>> On 16/02/2015 15:47, Stefan Priebe - Profihost AG wrote:
>>>>>>>
>>>>>>> Could it be that this is a results of compiling qemu with --enable-debug
>>>>>>> to get debugging symbols?
>>>>>
>>>>> Yes.
>>> *urg* my fault - sorry. Is there a way to get debugging symbols without
>>> using enable-debug / getting slower performance?
>>
>> Yes, just do nothing ("--enable-debug-info" is the default;
>> "--enable-debug" enables debug info _and_ turns off optimization).
> 
> If I do not enable-debug dh_strip does not extract any debugging symbols.

Maybe you forgot --disable-strip?

Regards,
Andreas

-- 
SUSE Linux GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
GF: Felix Imendörffer, Jane Smithard, Jennifer Guild, Dilip Upmanyu,
Graham Norton; HRB 21284 (AG Nürnberg)

Re: [Qemu-devel] slow speed for virtio-scsi since qemu 2.2

[Stefan Priebe]

Am 16.02.2015 um 16:50 schrieb Andreas Färber:
> Am 16.02.2015 um 16:41 schrieb Stefan Priebe - Profihost AG:
>>> Am 16.02.2015 um 15:49 schrieb Paolo Bonzini <pbonzini@redhat.com>:
>>>
>>>
>>>
>>> On 16/02/2015 15:47, Stefan Priebe - Profihost AG wrote:
>>>>>>>>
>>>>>>>> Could it be that this is a results of compiling qemu with --enable-debug
>>>>>>>> to get debugging symbols?
>>>>>>
>>>>>> Yes.
>>>> *urg* my fault - sorry. Is there a way to get debugging symbols without
>>>> using enable-debug / getting slower performance?
>>>
>>> Yes, just do nothing ("--enable-debug-info" is the default;
>>> "--enable-debug" enables debug info _and_ turns off optimization).
>>
>> If I do not enable-debug dh_strip does not extract any debugging symbols.
>
> Maybe you forgot --disable-strip?

Thanks!

Stefan

>
> Regards,
> Andreas
>

Re: [Qemu-devel] slow speed for virtio-scsi since qemu 2.2

[Andrey Korolyov]

On Mon, Feb 16, 2015 at 5:47 PM, Stefan Priebe - Profihost AG
<s.priebe@profihost.ag> wrote:
> Hi,
> Am 16.02.2015 um 15:44 schrieb Paolo Bonzini:
>>
>>
>> On 16/02/2015 15:43, Stefan Priebe - Profihost AG wrote:
>>> Hi,
>>>
>>> Am 16.02.2015 um 13:24 schrieb Paolo Bonzini:
>>>>
>>>>
>>>> On 15/02/2015 19:46, Stefan Priebe wrote:
>>>>>
>>>>> while i get a constant random 4k i/o write speed of 20.000 iops with
>>>>> qemu 2.1.0 or 2.1.3. I get jumping speeds with qemu 2.2 (jumping between
>>>>> 500 iops and 15.000 iop/s).
>>>>>
>>>>> If i use virtio instead of virtio-scsi speed is the same between 2.2 and
>>>>> 2.1.
>>>>
>>>> http://wiki.qemu.org/Contribute/ReportABug
>>>>
>>>> What is your command line?
>>>
>>> Could it be that this is a results of compiling qemu with --enable-debug
>>> to get debugging symbols?
>>
>> Yes.
>
> *urg* my fault - sorry. Is there a way to get debugging symbols without
> using enable-debug / getting slower performance?

Hi Stefan, splitdebug will help you there. Also this is a standard way
to ship debugging symbols in most distribuitions, so I wonder if you
may use just a generic build skeleton for this task...

Re: [Qemu-devel] slow speed for virtio-scsi since qemu 2.2

[Stefan Priebe - Profihost AG]

Hi,

> Am 16.02.2015 um 15:58 schrieb Andrey Korolyov <andrey@xdel.ru>:
> 
> On Mon, Feb 16, 2015 at 5:47 PM, Stefan Priebe - Profihost AG
> <s.priebe@profihost.ag> wrote:
>> Hi,
>>> Am 16.02.2015 um 15:44 schrieb Paolo Bonzini:
>>> 
>>> 
>>>> On 16/02/2015 15:43, Stefan Priebe - Profihost AG wrote:
>>>> Hi,
>>>> 
>>>>> Am 16.02.2015 um 13:24 schrieb Paolo Bonzini:
>>>>> 
>>>>> 
>>>>>> On 15/02/2015 19:46, Stefan Priebe wrote:
>>>>>> 
>>>>>> while i get a constant random 4k i/o write speed of 20.000 iops with
>>>>>> qemu 2.1.0 or 2.1.3. I get jumping speeds with qemu 2.2 (jumping between
>>>>>> 500 iops and 15.000 iop/s).
>>>>>> 
>>>>>> If i use virtio instead of virtio-scsi speed is the same between 2.2 and
>>>>>> 2.1.
>>>>> 
>>>>> http://wiki.qemu.org/Contribute/ReportABug
>>>>> 
>>>>> What is your command line?
>>>> 
>>>> Could it be that this is a results of compiling qemu with --enable-debug
>>>> to get debugging symbols?
>>> 
>>> Yes.
>> 
>> *urg* my fault - sorry. Is there a way to get debugging symbols without
>> using enable-debug / getting slower performance?
> 
> Hi Stefan, splitdebug will help you there. Also this is a standard way
> to ship debugging symbols in most distribuitions, so I wonder if you
> may use just a generic build skeleton for this task...

I'm using enable-debug with dh_strip from Debian

Stefan