Despite the promise of 34% better performance per watt,
Matthew Leeds, the vice president of IT operations for Gracenote, uses quad-core Opteron chips but won't upgrade to the six-core chip until he tests it in his own data center against Intel's latest chip release. He needs evidence that Istanbul makes sense from a cost and a performance perspective.
"There are a lot of metrics that get bounced around, but we benchmark hardware with our specific apps before upgrading," Leeds said. "We have a couple different types of applications -- some are memory bound rather than CPU bound -- so I want to see how it performs for both, and I would also want to see power draw per server, because we have a power budget."Multiple cores aren't for everyone
Not all applications are designed to take advantage of multiple cores, so users should consider their applications before upgrading, experts say. Applications that do not divide workloads, for instance, run fine with single- or dual-core CPUs, so those systems, like mail servers and Web servers, won't improve on a six-core chip, according to testing reports.
But for applications that run in parallel, the more cores the better. These applications can divide workloads to run on many cores; things like heavy high-performance computing workloads, large databases and virtualization, said Insight 64's CPU expert Nathan Brookwood.
Other IT pros are underwhelmed by the new six-core chips. Istanbul "doesn't seem that interesting," wrote one user on the IT community site Ars OpenForum, "other than as a drop-in CPU replacement upgrade to existing machines or as a new purchase to keep your platform as similar as possible to other servers you already own."
It appears to me that the additional cores are only marginally useful there," a systems integrator wrote, "as the memory interface remains at dual-channel DDR2-800. With only an 8 MB L3 [Level 3] cache, those extra cores will be starved for data, especially in databases and virtualization."
"The areas where [Istanbul] will best demonstrate advantages is database management systems, especially back-end, and in virtualization environments," said Nathan Brookwood, Insight 64's CPU expert. "Everybody and his brother is rushing to consolidate single-app systems onto virtual servers, so for those servers hosting hundreds of VMs, this is a sweet chip."
In cases where Istanbul will yield better performance because it is drop-in-compatible with previous generation dual core and quad-core processors, Brookwood expects quick adoption of the six-core chip. "It drops into the same exact socket as a dual-core or quad-core chip, so a customer can get twice as much computational power or more without using any more power," Brookwood said. "Upgrading to this chip can make a rack do twice the work it did before without adding heat."Istanbul vs. Nehalem
This is in contrast to Intel's latest chip upgrade, Nehalem, which is not upgrade-compatible with previous-generation Xeon chips, Brookwood said. "The Intel Xeon 5500 is not backward-compatible -- so even though it is a very compelling product, CIOs have to wheel out their old servers and buy entirely new ones to use the new Intel Xeon chips," he said.
The reason the latest Xeons aren't upgrade-compatible with previous-generation chips is that the new Nehalems have memory controllers directly on the CPU for the first time. "While that is a great move for performance, it also obsoletes all the prior-generation processors for upgrades," Brookwood said.
AMD's next chip, the 12-core processor code-named "Magny Cours" due out next year will not be drop-in compatible with any of the previous generation Opteron chips.
Systems based on six-core AMD Opteron processors are expected to come online later this month from server vendors including Cray, Dell, HP, IBM and Sun Microsystems, along with support from motherboard and infrastructure partners. HE, SE and EE versions of the Six-Core AMD Opteron processor are planned for the second half of 2009.
Pricing for the Istanbul line is as follows: AMD Opteron model 8435 (2.6 GHz, 75 watt) is $2,649; AMD Opteron model 8431 (2.4 GHz, 75 watt) is $2,149; AMD Opteron model 2435 (2.6 GHz 75 watt) is $989; AMD Opteron model 2431 (2.4 GHz, 75 watt) is $698; and the AMD Opteron model 2427 (2.2 GHz, 75 watt) is priced at $455.