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On 13/11/2014 21:21, Cousin Ricky wrote:
> My hardware is a Dell Inspiron 17R with Intel Core i7 (8 cores).
Isn't that 4 cores with HT ? (for povray, it would be worth 5 cores, YMMV)
--
IQ of crossposters with FU: 100 / (number of groups)
IQ of crossposters without FU: 100 / (1 + number of groups)
IQ of multiposters: 100 / ( (number of groups) * (number of groups))
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Le_Forgeron <jgr### [at] free fr> wrote:
> On 13/11/2014 21:21, Cousin Ricky wrote:
> > My hardware is a Dell Inspiron 17R with Intel Core i7 (8 cores).
>
> Isn't that 4 cores with HT ? (for povray, it would be worth 5 cores, YMMV)
I've seen "quad core" in literature not attached to this particular model, but
in the POV-Ray statistics, there is a clear 8-to-1 ratio between CPU times and
elapsed times. Does this mean that there are 2 CPUs in each core?
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Le 14/11/2014 00:36, Cousin Ricky a écrit :
> Le_Forgeron <jgr### [at] freefr> wrote:
>> On 13/11/2014 21:21, Cousin Ricky wrote:
>>> My hardware is a Dell Inspiron 17R with Intel Core i7 (8 cores).
>>
>> Isn't that 4 cores with HT ? (for povray, it would be worth 5 cores, YMMV)
>
> I've seen "quad core" in literature not attached to this particular model, but
> in the POV-Ray statistics, there is a clear 8-to-1 ratio between CPU times and
> elapsed times. Does this mean that there are 2 CPUs in each core?
>
>
Sort of... there is two full set of registers in each core, allowing to
run two code in parallel... as long as they do not need the same
resources from the core.
at 100% cpu like povray, yes there is a 8:1 ratio between cpu times and
wall-clock time. Yet, if the scheduler of the operating system is not
too bad, if you force povray to run on less threads (with -WT<number>
option), you can get some surprise like -WT8 is not twice faster that -WT4.
With good schedulers, povray -WT4 would run one thread per core, leaving
the other set of registers idle or used by something else.
--
Just because nobody complains does not mean all parachutes are perfect.
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On 14-11-2014 12:59, Le_Forgeron wrote:
> Le 14/11/2014 00:36, Cousin Ricky a écrit :
>> Le_Forgeron <jgr### [at] freefr> wrote:
>>> On 13/11/2014 21:21, Cousin Ricky wrote:
>>>> My hardware is a Dell Inspiron 17R with Intel Core i7 (8 cores).
>>>
>>> Isn't that 4 cores with HT ? (for povray, it would be worth 5 cores, YMMV)
>>
>> I've seen "quad core" in literature not attached to this particular model, but
>> in the POV-Ray statistics, there is a clear 8-to-1 ratio between CPU times and
>> elapsed times. Does this mean that there are 2 CPUs in each core?
>>
>>
> Sort of... there is two full set of registers in each core, allowing to
> run two code in parallel... as long as they do not need the same
> resources from the core.
>
> at 100% cpu like povray, yes there is a 8:1 ratio between cpu times and
> wall-clock time. Yet, if the scheduler of the operating system is not
> too bad, if you force povray to run on less threads (with -WT<number>
> option), you can get some surprise like -WT8 is not twice faster that -WT4.
>
> With good schedulers, povray -WT4 would run one thread per core, leaving
> the other set of registers idle or used by something else.
>
>
Talking of which, is there a difference between -WT and +WT? I get the
impression that both are used indiscriminately.
Thomas
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On 11/14/2014 5:59 AM, Le_Forgeron wrote:
> Le 14/11/2014 00:36, Cousin Ricky a écrit :
>> Le_Forgeron <jgr### [at] freefr> wrote:
>>> On 13/11/2014 21:21, Cousin Ricky wrote:
>>>> My hardware is a Dell Inspiron 17R with Intel Core i7 (8 cores).
>>>
>>> Isn't that 4 cores with HT ? (for povray, it would be worth 5 cores, YMMV)
>>
>> I've seen "quad core" in literature not attached to this particular model, but
>> in the POV-Ray statistics, there is a clear 8-to-1 ratio between CPU times and
>> elapsed times. Does this mean that there are 2 CPUs in each core?
>>
>>
> Sort of... there is two full set of registers in each core, allowing to
> run two code in parallel... as long as they do not need the same
> resources from the core.
>
> at 100% cpu like povray, yes there is a 8:1 ratio between cpu times and
> wall-clock time. Yet, if the scheduler of the operating system is not
> too bad, if you force povray to run on less threads (with -WT<number>
> option), you can get some surprise like -WT8 is not twice faster that -WT4.
>
> With good schedulers, povray -WT4 would run one thread per core, leaving
> the other set of registers idle or used by something else.
>
>
Yep. Pretty much that. I've noticed that my work computer (core i3, dual
core) isn't quite as fast as my desktop PC (a Core2 Quad), even though
it appears to have 4 cores to applications.
I forget exactly what hyperthreading does, but it does give a bit of a
boost to multi-threaded applications.
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On 14/11/2014 13:06, Thomas de Groot wrote:
> On 14-11-2014 12:59, Le_Forgeron wrote:
>> Le 14/11/2014 00:36, Cousin Ricky a écrit :
>>> Le_Forgeron <jgr### [at] freefr> wrote:
>>>> On 13/11/2014 21:21, Cousin Ricky wrote:
>>>>> My hardware is a Dell Inspiron 17R with Intel Core i7 (8 cores).
>>>>
>>>> Isn't that 4 cores with HT ? (for povray, it would be worth 5 cores,
>>>> YMMV)
>>>
>>> I've seen "quad core" in literature not attached to this particular
>>> model, but
>>> in the POV-Ray statistics, there is a clear 8-to-1 ratio between CPU
>>> times and
>>> elapsed times. Does this mean that there are 2 CPUs in each core?
>>>
>>>
>> Sort of... there is two full set of registers in each core, allowing to
>> run two code in parallel... as long as they do not need the same
>> resources from the core.
>>
>> at 100% cpu like povray, yes there is a 8:1 ratio between cpu times and
>> wall-clock time. Yet, if the scheduler of the operating system is not
>> too bad, if you force povray to run on less threads (with -WT<number>
>> option), you can get some surprise like -WT8 is not twice faster that
>> -WT4.
>>
>> With good schedulers, povray -WT4 would run one thread per core, leaving
>> the other set of registers idle or used by something else.
>>
>>
> Talking of which, is there a difference between -WT and +WT? I get the
> impression that both are used indiscriminately.
>
> Thomas
Actually, for some option there is a difference between + and -
(usually one form disable the option, and the other enable it, with some
value).
For instance +KC and -KC are opposite of each other.
But +H and -H are happily setting both the height of the output.
Now, if I could find a mnemonic to remember which one is enable and
which one is disable... that would be a great year.
--
IQ of crossposters with FU: 100 / (number of groups)
IQ of crossposters without FU: 100 / (1 + number of groups)
IQ of multiposters: 100 / ( (number of groups) * (number of groups))
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Thomas de Groot <tho### [at] degrootorg> wrote:
> Talking of which, is there a difference between -WT and +WT? I get the
> impression that both are used indiscriminately.
>
> Thomas
"Inflammable means flammable? What a country!"
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Am 14.11.2014 19:03, schrieb Le_Forgeron:
> Actually, for some option there is a difference between + and -
> (usually one form disable the option, and the other enable it, with some
> value).
>
> For instance +KC and -KC are opposite of each other.
>
> But +H and -H are happily setting both the height of the output.
>
> Now, if I could find a mnemonic to remember which one is enable and
> which one is disable... that would be a great year.
Uh... how about "+" adds something (turns it on), while "-" removes
something (turns it off)?
Not too difficult, is it ;-)
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On 15-11-2014 3:47, clipka wrote:
> Am 14.11.2014 19:03, schrieb Le_Forgeron:
>
>> Actually, for some option there is a difference between + and -
>> (usually one form disable the option, and the other enable it, with some
>> value).
>>
>> For instance +KC and -KC are opposite of each other.
>>
>> But +H and -H are happily setting both the height of the output.
>>
>> Now, if I could find a mnemonic to remember which one is enable and
>> which one is disable... that would be a great year.
>
> Uh... how about "+" adds something (turns it on), while "-" removes
> something (turns it off)?
>
> Not too difficult, is it ;-)
>
LOL. I must say that where on/off is concerned, I do not have much
problem with +/-. It is those cases where there is no such thing and
where you can either use + or - for the same result that I begin to feel
itchy. It confuses the issue and as one does not always remember which
of those bloody settings can or cannot be switched... ;-)
Thomas
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Thomas de Groot <tho### [at] degrootorg> wrote:
> LOL. I must say that where on/off is concerned, I do not have much
> problem with +/-. It is those cases where there is no such thing and
> where you can either use + or - for the same result that I begin to feel
> itchy. It confuses the issue and as one does not always remember which
> of those bloody settings can or cannot be switched... ;-)
I just make a habit of using + unless I want to turn something off. That way
the question never comes up.
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