- Joined
- Sep 27, 2003
- Location
- St. Paul, MN
I fell for this, thought others would like the read. Not sure if this is old or new, but here it is nonetheless...
The /prefetch:# flag is looked at by the OS when we create the process -- however, it has one (and only one) purpose. We add the passed number to the hash. Why? WMP is a multipurpose application and may do many different things. The DLLs and code that it touches will be very different when playing a WMV than when playing a DVD, or when ripping a CD, or when listening to a Shoutcast stream, or any of the other things that WMP can do. If we only had one hash for WMP, then the prefetch would only be correct for one such use. Having incorrect prefetch data would not be a fatal error -- it'd just load pages into memory that'd never get used, and then get swapped back out to disk as soon as possible. Still, it's counterproductive. By specifying a /prefetch:# flag with a different number for each "mode" that WMP can do, each mode gets its own separate hash file, and thus we properly prefetch.
[Update: Ryan Myers reinforces this conclusion when he says, "I suspect that the 'add /prefetch:1 to make rocket go now' urban legend will never die, though. I know that at least one major company ships products with it in their shortcuts, without ever asking us... just for good measure, I guess.
"]
My advice? If someone tells you to make this "tweak," scratch them off your list of trusted information sources. They don't know what they're talking about.
-Ryan Myers, a developer on Microsoft's Windows Client Performance Team
Original link
The /prefetch:# flag is looked at by the OS when we create the process -- however, it has one (and only one) purpose. We add the passed number to the hash. Why? WMP is a multipurpose application and may do many different things. The DLLs and code that it touches will be very different when playing a WMV than when playing a DVD, or when ripping a CD, or when listening to a Shoutcast stream, or any of the other things that WMP can do. If we only had one hash for WMP, then the prefetch would only be correct for one such use. Having incorrect prefetch data would not be a fatal error -- it'd just load pages into memory that'd never get used, and then get swapped back out to disk as soon as possible. Still, it's counterproductive. By specifying a /prefetch:# flag with a different number for each "mode" that WMP can do, each mode gets its own separate hash file, and thus we properly prefetch.
[Update: Ryan Myers reinforces this conclusion when he says, "I suspect that the 'add /prefetch:1 to make rocket go now' urban legend will never die, though. I know that at least one major company ships products with it in their shortcuts, without ever asking us... just for good measure, I guess.
"]My advice? If someone tells you to make this "tweak," scratch them off your list of trusted information sources. They don't know what they're talking about.
-Ryan Myers, a developer on Microsoft's Windows Client Performance Team
Original link
