By: Wilco (Wilco.Dijkstra.delete@this.ntlworld.com), January 25, 2017 4:41 pm
Room: Moderated Discussions
David Kanter (dkanter.delete@this.realworldtech.com) on January 25, 2017 7:15 am wrote:
> Wilco (Wilco.Dijkstra.delete@this.ntlworld.com) on January 25, 2017 3:22 am wrote:
> > Really? Are you claiming that CPUs, fabrics, memory controllers etc etc cannot be shared?
>
> Sure, they *can be* shared. But they *should not* be shared. Memory controllers are different,
> on-chip fabrics are different, power management is different, power delivery is different.
Every smart designer shares as much as possible - cars are a great example. Mobile cores today are far more server-like than you seem to think. Cache sizes, core counts, memory controllers, fabric width, ECC support etc can be configured as desired.
> The CPU core can be the same, but that involves sacrifices (smaller than ideal TLBs, smaller caches,
> lower power/core, etc.). The I/Os are radically different, since no phone has an off-chip cache
> coherent link in it. Some phones may have PCIe, none have 10GbE or 100GbE, or Infiniband.
Where is the sacrifice when the mobile oriented Cortex-A73 has more TLB entries than both Cortex-A72 and Haswell? And I don't believe anyone has ever lost sleep about a core being too low power... Most servers do not need an off-chip coherent fabric - we're talking about designing cost-effective servers using off-the-shelf components. Several ARM servers have had 10+GbE, SATA controllers and PCIe for a few years so it's likely standard IP is available for these.
Wilco
> Wilco (Wilco.Dijkstra.delete@this.ntlworld.com) on January 25, 2017 3:22 am wrote:
> > Really? Are you claiming that CPUs, fabrics, memory controllers etc etc cannot be shared?
>
> Sure, they *can be* shared. But they *should not* be shared. Memory controllers are different,
> on-chip fabrics are different, power management is different, power delivery is different.
Every smart designer shares as much as possible - cars are a great example. Mobile cores today are far more server-like than you seem to think. Cache sizes, core counts, memory controllers, fabric width, ECC support etc can be configured as desired.
> The CPU core can be the same, but that involves sacrifices (smaller than ideal TLBs, smaller caches,
> lower power/core, etc.). The I/Os are radically different, since no phone has an off-chip cache
> coherent link in it. Some phones may have PCIe, none have 10GbE or 100GbE, or Infiniband.
Where is the sacrifice when the mobile oriented Cortex-A73 has more TLB entries than both Cortex-A72 and Haswell? And I don't believe anyone has ever lost sleep about a core being too low power... Most servers do not need an off-chip coherent fabric - we're talking about designing cost-effective servers using off-the-shelf components. Several ARM servers have had 10+GbE, SATA controllers and PCIe for a few years so it's likely standard IP is available for these.
Wilco
