By: David Kanter (dkanter.delete@this.realworldtech.com), January 25, 2017 7:10 pm
Room: Moderated Discussions
Wilco (Wilco.Dijkstra.delete@this.ntlworld.com) on January 25, 2017 4:41 pm wrote:
> 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.
Cores have been shared for some folks (Intel, AMD), but not for most others. Cavium, QC all use different cores than client SoCs.
> > 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?
Those aren't server cores, those are cores that are sometimes used in servers (Haswell). Look at the POWER8 2K/core. That's far bigger than Intel.
Also, if the A73 has more TLB entries than the A72...that should tell you something about the A72.
>And I don't believe anyone has ever lost sleep about a core being too low power...
Agreed.
> Most servers do not need an off-chip coherent fabric - we're talking about designing cost-effective
> servers using off-the-shelf components.
About 70% of the market is 2S servers. So that's most of the market. Cavium has an off-chip link, so does AMD, IBM, Oracle, probably Qualcomm, and others.
> 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.
SATA controllers aren't exactly magical or high value. PCIe is often quite tricky, especially new versions. 10GbE is pretty easy today.
David
> 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.
Cores have been shared for some folks (Intel, AMD), but not for most others. Cavium, QC all use different cores than client SoCs.
> > 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?
Those aren't server cores, those are cores that are sometimes used in servers (Haswell). Look at the POWER8 2K/core. That's far bigger than Intel.
Also, if the A73 has more TLB entries than the A72...that should tell you something about the A72.
>And I don't believe anyone has ever lost sleep about a core being too low power...
Agreed.
> Most servers do not need an off-chip coherent fabric - we're talking about designing cost-effective
> servers using off-the-shelf components.
About 70% of the market is 2S servers. So that's most of the market. Cavium has an off-chip link, so does AMD, IBM, Oracle, probably Qualcomm, and others.
> 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.
SATA controllers aren't exactly magical or high value. PCIe is often quite tricky, especially new versions. 10GbE is pretty easy today.
David
