Windows on multicore: Why XP reigns supreme
Microsoft faces short term embarassment over Vista and Windows 7 speed
By Randall C. Kennedy, InfoWorld | Published 00:55, 23 January 09
Windows 7 beta
Windows 7 seems to be many things to many different people. To the enthusiast crowd, it's the cool new OS of the moment, the one that will fix all of Vista's ills and make the world right again. To desperate IT planners, it's a potential "third way" out of their current XP-versus-Vista predicament. But for the rest of us (that is, veteran Windows users who can see through the hype), Windows 7 is really just Windows Vista with some performance tweaks and an updated Explorer shell. It's a modest update that may or may not swing the public-perception pendulum back in Microsoft's favour.
It should come as no surprise that Windows 7 performs very much like its predecessor. In fact, during extensive multiprocess benchmark testing, Windows 7 essentially mirrored Vista in almost every scenario. Database tasks? Roughly 118 percent slower than XP on dual-core (Vista was 92 percent slower) and 19 percent slower than XP on quad-core (identical to Vista). Workflow? A respectable 38 percent slower than XP on dual-core (Vista was 98 percent slower) and 59 percent slower on quad-core (Vista was 66 percent slower).
Windows 7 also scales similarly to Vista when moving from dual- to quad-core. Our database workload showed a whopping 571 percent improvement with the addition of two more cores (Vista showed a 492 percent gain), while our workflow workload experienced a less compelling 15 percent speed-up (Vista gained 58 percent on this test). This latter discrepancy may have more to do with limitations in the MAPI subsystem's scalability (Windows 7 was already 44 percent faster than Vista on dual-core for this particular workload) than any real limitation in Windows 7.
Regardless of how you slice the numbers, Windows 7 and Vista remain birds of a feather and clearly a very different species of animal from Windows XP. You can see this divergence in the overall execution path complexity for Windows 7. Like Vista, this new Windows chews up a lot more CPU cycles per transaction loop than XP -- from 39 to 68 percent more on dual-core and from 19 to 51 percent more on quad-core (the lower figures in each case representing the workflow workload, and the higher figures the database workload).
Any illusions about Windows 7 somehow being leaner or more efficient than Vista can now be thrown out the window, right along with the infamous "new kernel" myth and related rumours and misconceptions.
But it's not all bad news with Windows 7. Microsoft's new OS has a clear multicore scalability advantage over both Windows XP and Windows Vista, especially on less I/O-bound tasks like our multiprocess database workload. (We can thank SQL Server 2008 for that one.)
In fact, with its second-generation multicore tweaking (good-bye, global lock!), Windows 7 is poised to overtake XP even earlier than Windows Vista -- perhaps at 16 or 24 cores. In the meantime, you certainly won't lose anything by moving from Vista to Windows 7, and you may even gain a few seconds here and there, thanks to its better kernel tuning.
