Saturday, November 09, 2013
Saturday, September 28, 2013
I'd been wondering about quite how Apple had been getting the impressive performance improved reported in some of the iPhone 5S v iPone 5 benchmarks. The improvement is better than could be explained just by the ISA changes, and it seemed unlikely that Apple would have made microarchitectural improvements that impacted only 64-bit mode. I've just read an article which sets out how Apple are exploiting the ARM64 architecture to speed up the critical software operations of object creation and destruction. To summarise, when supporting a 8 Gbyte virtual user address space (iOS7), a 64-bit value can contain many bits of information in addition to those needed to hold the address, and this is what Apple has done. The article's author, Mike Ash, reports very significant speed-ups (1.9x to 2.4x):
"My casual benchmarking indicates that basic object creation and destruction takes about 380ns on a 5S running in 32-bit mode, while it's only about 200ns when running in 64-bit mode. If any instance of the class has ever had a weak reference and an associated object set, the 32-bit time rises to about 480ns, while the 64-bit time remains around 200ns for any instances that were not themselves the target."
Thursday, August 29, 2013
I've just started playing with IFTTT (IF This Then That). So far I've set things up to copy my app.net stream to Twitter and to send a message on app.net when I submit a new blog post - just to see how things work. I think there are some useful things I'll do with pictures - making sure that new Facebook, Foursquare and other photos get filed somewhere central.
Thursday, August 15, 2013
Saturday, June 08, 2013
Great news. The Tom Tom Club will be playing in Bristol in a couple of weeks. Until it happens you'll have to keep happy with http://www.npr.org/2010/10/06/130323805/tom-tom-club-tiny-desk-concert
Sunday, April 07, 2013
Well this blog has gone really quiet over the past few months, hasn't it? Why? It's a mixture of things: I've been busy; I've been using Facebook for tittle-tattle that might otherwise have made it here; and I've not simultaneously had both the urge to write thoughtfully and the time to do it. And that hasn't really changed, but I do think that Mike The Mad Biologist deserves a mention on my blog, as well as the more ephemeral Facebook and Twitter. Go take a look.