Hi,
When hyper-threading was first released it got some bad reviews for a number of reasons.
Half of this was due to people comparing single-CPU performance with hyper-threading performance, where the 10% to 60% gains of hyper-threading were offset by the performance reduction involved with SMP (re-entrancy locking, cache thrashing and other scalability problems) and a lack of software designed for multi-CPU.
Part of it was also due to OS's that weren't "hyper-threading aware". For example, when there's 2 threads to run some OSs will run both of them on the same core while another core does nothing, instead of running one on each core.
With the industry adopting multi-core, the software industry is (slowly) shifting to software designed for multi-CPU, and any computer with SMP (multi-core or "multi-socket") will have the SMP overhead anyway. Also, recent versions of most OSs are hyper-threading aware. This means all of the "disadvantages" (or all of the reasons for the bad reviews) are disappearing. In addition Intel has improved it's hyper-threading since it's introduction.
For hyper-threading, the benefits come from keeping the CPU's resources as busy as possible. For example, when one logical CPU needs to wait (cache miss, pipeline flush, etc) the other logical CPU can make good use of the CPU resources that would otherwise be doing nothing. For multi-core CPUs where the same system bus is shared by multiple cores, the cost of cache misses, etc will be worse due to the additional bus traffic, and hyper-threading will be more important to keep the CPUs cores busy.
Anyway, I'm hoping the Inquirer article is a hoax.
In the hope of finding out, I've posted a message on the Intel developer forums at:
http://softwareforums.intel.com/ids/board/message?board.id=42&message.id=912.
Cheers,
Brendan
