By: coppice (coppice.delete@this.dis.org), January 8, 2015 11:38 pm
Room: Moderated Discussions
Mark Roulo (nothanks.delete@this.xxx.com) on January 8, 2015 6:37 pm wrote:
> juanrga (nospam.delete@this.juanrga.com) on January 7, 2015 6:03 am wrote:
> > I recall Aaron asking me why I believed that mixing VLIW with
> > RA was a good idea. Funny, because we know now that
> > Denver is an in-order VLIW+RA core that outperforms wide OoO cores such as Cyclone or Haswell.
>
> Have you not noticed that nVidia did not select the fastest 15W Haswell CPU they could?
>
> The 2955U Celeron is a 15W TDP part with no hyperthreading, a clockspeed
> of 1.4 GHz and 2 MB of L3 cache. Turbo-boost is disabled.
>
> The 4650U is *also* a 15W TDP Haswell part, but it has a base frequency
> of 1.7 GHz, 4 MB of L3 cache and will turbo to 3.3 GHz.
>
> Eyeballing the nVidia chart, the Denver (@ 2.5GHz?) beat the 2955U by about 10% on SpecInt2000. My guess is
> that a 4650U would beat the Denver chip by close to 2:1. When you lose by 2:1, you aren't "outperforming".
The 4650U is a very expensive chip, while dual core denvers are going into tablets. Is that a fair comparison? I guess winning, rather than fairness, was uppermost when the comparison with the 2955U was made, but you have to look beyond one parameter, like watts.
> If you want to do a technical comparison between Denver and Haswell, you really
> do have to pick the fastest relevant Haswell part, not the slowest.
> Why are you so invested in 1000 core CPUs?
He seems to believe that research into X inevitably produces a really great X. Meanwhile he gets inspiration from papers which show ways for manycore to do a little better at the subset of things manycore does well, and ignores that troublesome subset issue.
> juanrga (nospam.delete@this.juanrga.com) on January 7, 2015 6:03 am wrote:
> > I recall Aaron asking me why I believed that mixing VLIW with
> > RA was a good idea. Funny, because we know now that
> > Denver is an in-order VLIW+RA core that outperforms wide OoO cores such as Cyclone or Haswell.
>
> Have you not noticed that nVidia did not select the fastest 15W Haswell CPU they could?
>
> The 2955U Celeron is a 15W TDP part with no hyperthreading, a clockspeed
> of 1.4 GHz and 2 MB of L3 cache. Turbo-boost is disabled.
>
> The 4650U is *also* a 15W TDP Haswell part, but it has a base frequency
> of 1.7 GHz, 4 MB of L3 cache and will turbo to 3.3 GHz.
>
> Eyeballing the nVidia chart, the Denver (@ 2.5GHz?) beat the 2955U by about 10% on SpecInt2000. My guess is
> that a 4650U would beat the Denver chip by close to 2:1. When you lose by 2:1, you aren't "outperforming".
The 4650U is a very expensive chip, while dual core denvers are going into tablets. Is that a fair comparison? I guess winning, rather than fairness, was uppermost when the comparison with the 2955U was made, but you have to look beyond one parameter, like watts.
> If you want to do a technical comparison between Denver and Haswell, you really
> do have to pick the fastest relevant Haswell part, not the slowest.
> Why are you so invested in 1000 core CPUs?
He seems to believe that research into X inevitably produces a really great X. Meanwhile he gets inspiration from papers which show ways for manycore to do a little better at the subset of things manycore does well, and ignores that troublesome subset issue.