Feeds

Merced: the case for the defence

Executing instructions in order is OK, reader says

  • alert
  • submit to reddit

Security for virtualized datacentres

A reader has replied to a story we wrote yesterday that claimed Merced compilers were in bad shape. Story: Optimisers not optimistic about Merced Here are his comments: "I agree that Merced will only execute instructions in order. Load instructions just queue the request to memory. They do not wait until the result is available. If an instruction which requires that data executes before it is available then that instruction will stall and all the instructions behind it will stall. "Now this sounds very bad but it is not in practice. Firstly all compilers will always put as much space as possible between a load and its use. Secondly in an Out-Of-Order(OOO) execution processor if an instruction stalls then other instructions can issue BUT this in practice is limited. "Usually only a handful of instructions will be issued because they are relying on the results of the stalled instruction. "The gap between CPU speed and memory speed is now so vast that a few token instructions executed out of order only fills a small percentage of the wait. "The main disadvantage of the Merced is when data resides on the second level cache then the Out-Of-Order execution processor may fill those few cycles more efficiently. "To make a processor execute Out-Of-Order adds a lot of circuitry and can slow down the clock speed. I assume Merced uses these released resources for other kinds of optimisation." ®

Security and trust: The backbone of doing business over the internet

More from The Register

next story
Phones 4u slips into administration after EE cuts ties with Brit mobe retailer
More than 5,500 jobs could be axed if rescue mission fails
JINGS! Microsoft Bing called Scots indyref RIGHT!
Redmond sporran metrics get one in the ten ring
Driving with an Apple Watch could land you with a £100 FINE
Bad news for tech-addicted fanbois behind the wheel
Phones 4u website DIES as wounded mobe retailer struggles to stay above water
Founder blames 'ruthless network partners' for implosion
Sony says year's losses will be FOUR TIMES DEEPER than thought
Losses of more than $2 BILLION loom over troubled Japanese corp
Radio hams can encrypt, in emergencies, says Ofcom
Consultation promises new spectrum and hints at relaxed licence conditions
Why Oracle CEO Larry Ellison had to go ... Except he hasn't
Silicon Valley's veteran seadog in piratical Putin impression
Big Content Australia just blew a big hole in its credibility
AHEDA's research on average content prices did not expose methodology, so appears less than rigourous
prev story

Whitepapers

Secure remote control for conventional and virtual desktops
Balancing user privacy and privileged access, in accordance with compliance frameworks and legislation. Evaluating any potential remote control choice.
WIN a very cool portable ZX Spectrum
Win a one-off portable Spectrum built by legendary hardware hacker Ben Heck
Storage capacity and performance optimization at Mizuno USA
Mizuno USA turn to Tegile storage technology to solve both their SAN and backup issues.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?
The next step in data security
With recent increased privacy concerns and computers becoming more powerful, the chance of hackers being able to crack smaller-sized RSA keys increases.