a*l
2 楼
what's the surprising part?
【在 R*******N 的大作中提到】
: 哪有Intel Itanium的性能报告呢？
【在 R*******N 的大作中提到】
: 哪有Intel Itanium的性能报告呢？
R*N
3 楼
It is too low, why not 80%?
Two processors running for the same program ...
【在 a****l 的大作中提到】
: what's the surprising part?
Two processors running for the same program ...
【在 a****l 的大作中提到】
: what's the surprising part?
a*l
4 楼
why do you think two processors running the same program should be 80%
faster on dual-core?
【在 R*******N 的大作中提到】
: It is too low, why not 80%?
: Two processors running for the same program ...
faster on dual-core?
【在 R*******N 的大作中提到】
: It is too low, why not 80%?
: Two processors running for the same program ...
R*N
5 楼
Why not? hehe,
Anyway, do you have any citation (report or weblink) about that 30% performence? I read it somewhere, but forget its source...Many thanks!
【在 a****l 的大作中提到】
: why do you think two processors running the same program should be 80%
: faster on dual-core?
Anyway, do you have any citation (report or weblink) about that 30% performence? I read it somewhere, but forget its source...Many thanks!
【在 a****l 的大作中提到】
: why do you think two processors running the same program should be 80%
: faster on dual-core?
b*e
6 楼
The truth is:
if your compiler can't support parallel programming, you can't get the 80%
increasement in execution speed.
the intermediate code generator is the bottle neck for the Dual Core
performance.The compiler is not that efficient to work with the Dual Core.
if your compiler can't support parallel programming, you can't get the 80%
increasement in execution speed.
the intermediate code generator is the bottle neck for the Dual Core
performance.The compiler is not that efficient to work with the Dual Core.
p*f
7 楼
极端情况，如果你的程序并行度为0， dual-core比single-core还慢。
performence? I read it somewhere, but forget its source...Many thanks!
【在 R*******N 的大作中提到】
: Why not? hehe,
: Anyway, do you have any citation (report or weblink) about that 30% performence? I read it somewhere, but forget its source...Many thanks!
performence? I read it somewhere, but forget its source...Many thanks!
【在 R*******N 的大作中提到】
: Why not? hehe,
: Anyway, do you have any citation (report or weblink) about that 30% performence? I read it somewhere, but forget its source...Many thanks!
R*N
8 楼
如果是２个线程，放双核和单核上跑，单核执行完２秒，双核估计得多少？能１秒跑完？
【在 p****f 的大作中提到】
: 极端情况，如果你的程序并行度为0， dual-core比single-core还慢。
:
: performence? I read it somewhere, but forget its source...Many thanks!
【在 p****f 的大作中提到】
: 极端情况，如果你的程序并行度为0， dual-core比single-core还慢。
:
: performence? I read it somewhere, but forget its source...Many thanks!
a*l
9 楼
I believe most clasic books on parallel computer architecture have answers
to this question.
完？
【在 R*******N 的大作中提到】
: 如果是２个线程，放双核和单核上跑，单核执行完２秒，双核估计得多少？能１秒跑完？
to this question.
完？
【在 R*******N 的大作中提到】
: 如果是２个线程，放双核和单核上跑，单核执行完２秒，双核估计得多少？能１秒跑完？
R*N
10 楼
你有reference么？主要是share data那部分对多处理器冲击如何？
记得有讲因为数据share的冲突，双核不仅不能接近2倍速，只能达到单核的130%，这样
性价比就不合算了。
【在 a****l 的大作中提到】
: I believe most clasic books on parallel computer architecture have answers
: to this question.
:
: 完？
记得有讲因为数据share的冲突，双核不仅不能接近2倍速，只能达到单核的130%，这样
性价比就不合算了。
【在 a****l 的大作中提到】
: I believe most clasic books on parallel computer architecture have answers
: to this question.
:
: 完？
L*a
11 楼
see Amdahl's law :
http://en.wikipedia.org/wiki/Amdahl%27s_law
it's a law saying that when you stack up CPUs together, you can
only get sub-linear speed-up of the real computation power.
This is because of a few of bottlenecks, e.g. communication bottlenecks,
resource access bottlenecks ...
http://en.wikipedia.org/wiki/Amdahl%27s_law
it's a law saying that when you stack up CPUs together, you can
only get sub-linear speed-up of the real computation power.
This is because of a few of bottlenecks, e.g. communication bottlenecks,
resource access bottlenecks ...
R*N
12 楼
多谢！请问哪有实测的数据没？比如因特尔双核之类的。
我记得原来看个文章讲，因特尔也只有30%的提高，很符合这个Amdahl law。但现在想
不起哪的数据了。
【在 L****a 的大作中提到】
: see Amdahl's law :
: http://en.wikipedia.org/wiki/Amdahl%27s_law
: it's a law saying that when you stack up CPUs together, you can
: only get sub-linear speed-up of the real computation power.
: This is because of a few of bottlenecks, e.g. communication bottlenecks,
: resource access bottlenecks ...
我记得原来看个文章讲，因特尔也只有30%的提高，很符合这个Amdahl law。但现在想
不起哪的数据了。
【在 L****a 的大作中提到】
: see Amdahl's law :
: http://en.wikipedia.org/wiki/Amdahl%27s_law
: it's a law saying that when you stack up CPUs together, you can
: only get sub-linear speed-up of the real computation power.
: This is because of a few of bottlenecks, e.g. communication bottlenecks,
: resource access bottlenecks ...
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