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From: Jaimie Vandenbergh on 14 Apr 2010 13:02 On Wed, 14 Apr 2010 17:19:33 +0100, Bruce Horrocks <07.013(a)scorecrow.com> wrote: >Jamie has the right explanation but the keypress example isn't a good >one and it has thrown you off the scent. A process waiting for a >keypress is far too high level for the CPU to worry itself about >directly. Scheduling tasks for execution around a keypress wait will >always be an operating system task. Thanks for jumping in - I was never very good at CPU-level stuff! Cheers - Jaimie -- We're the technical experts. We were hired so that management could ignore our recommendations and tell us how to do our jobs. -- Mike Andrews
From: zoara on 14 Apr 2010 13:16 Peter Ceresole <peter(a)cara.demon.co.uk> wrote: > Jaimie Vandenbergh <jaimie(a)sometimes.sessile.org> wrote: > > > The new ones have cameras, GPS in the non-3G version, a gig of RAM > > and > > an SD card slot. > > If only... Then it might even be worth buying one. Oh yes, and with > Flash. Hey, look! Flash on the iPad! http://j.mp/aPfulQ *rimshot* -z- -- email: nettid1 at fastmail dot fm
From: Bruce Horrocks on 14 Apr 2010 16:29 On 14/04/2010 17:44, Tim Streater wrote: > For the second process, does it have a "proper" set of second registers > that can just take over, or does it have to save the first set and load > the registers up with the saved state from the other thread? I could > also see, that, either way, the cache won't have what it needs for the > second process anyway, so that may stall too, straightaway. Or does it > have two caches? I don't know the ins and outs of Intel's implementation but I would have thought that registers would be saved within the CPU to a second set. These are unlikely to be accessible to anything other than microcode. I assume that level 1 cache must be divided between the two cores so that while one is stalled waiting for its cache to be refilled, the second is ready to go. There is always the chance that both virtual CPUs simultaneously stall but that's to be expected because pipelining is not a magic bullet. > And your mention of time slice makes me wonder about that, too. That's > also going to be an OS scheduler decision - or is there extra hardware > so the OS can keep track of how much time each process has had? I only mentioned timeslice because it struck me that there could always be a situation in which a perfectly formed piece of code never stalls the CPU. In which case, something has to give in order that the virtual CPUs appear to be separate otherwise the operating system might think that one of them had failed. It's not a timeslice in the traditional OS sense. -- Bruce Horrocks Surrey England (bruce at scorecrow dot com)
From: Peter Ceresole on 14 Apr 2010 18:23 zoara <me18(a)privacy.net> wrote: > Hey, look! Flash on the iPad! http://j.mp/aPfulQ That url gives me an error message. Got another? -- Peter
From: zoara on 14 Apr 2010 18:55
Jaimie Vandenbergh <jaimie(a)sometimes.sessile.org> wrote: > On 14 Apr 2010 08:31:09 GMT, zoara <me18(a)privacy.net> wrote: > > >Ben Shimmin <bas(a)llamaselector.com> wrote: > >> David Empson <dempson(a)actrix.gen.nz>: > >> > >> [...] > >> > >> > I'm less certain about which options are new. The 15" now > > > > mentions a > >> > 1680x1050 optional display resolution (required if you want the > >> > antiglare option), and SSDs are available up to 512 GB. > >> > >> The higher resolution is definitely new. If I could change two > > > things > >> about my 2008 unibody MBP, it would be the battery life (mine > > > predates > >> the ones with the allegedly much improved batteries, and thus > >> struggles > >> to manage three hours) and the resolution; 1440x900 feels a bit > >> limiting > >> sometimes -- 1680x1050 would be lovely and it'd match my 20" > > > monitor > >> nicely too! > >> > > > >Battery life and heat here. I think mine's the Santa Rosa generation > > and > >it gets painfully hot. I hope the new ones are nice and cool. > > The previous generation to this were very cool too - I've hardly ever > managed to spin the fans on my late 2009 MBP. I know. I'm just worried that it's cyclic - they keep cranking CPU speeds until they cook enough customers that they decide a temperature-focused redesign is in order. Then they crank the speeds further and start cooking customers again. I'm hoping that my generation was just unusual (because most Mac laptops are pretty good, heatwise) but maybe I was just at the peak of a cycle, and these new ones are heading back up the slope. Then again, I don't *need* a new laptop, so maybe it's for the best if they are pretty hot - gives me a way to resist temptation... -z- -- email: nettid1 at fastmail dot fm |