General discussion
-
Topic
-
Windows: Stop the Swap!
LockedDisk swapping began in the days of magnetic-core mainframes, when RAM was unbelievably expensive. A single one-K core module cost many thousands of dollars. (I have one framed on my wall). Swapping to a DASD was a great way to share resources and increase utilization and performance.
Then came solid-state RAM, first dynamic and then static. The cost dropped significantly; I remember what a “bargain” I got when I bought a 16K static RAM S100 card at the Trenton Computerfest for “only” $125. Yes, 16K, not Meg.
I’m “experienced” enough to remember back to the dawn of Windows. In those days, the way to get screaming performance was to max your system with RAM, then go to the kernel executive options and disable disk swapping.
Then came Windows 95. Although it would run with 8M RAM, and wanted a swap file twice that size, when I told a system with 64M RAM to disable swapping in the executive, the system would not boot.
Such has been the way of Windows ever since. Computers have increased from tens of Megabytes of RAM, to hundreds of Megabytes, to Gigabytes and beyond. No matter how much RAM you give it, the Windows executive MUST have a swap file, larger than the amount of physical RAM. Try to prevent that, and you’re sunk.
Now let’s examine that premise for a moment. RAM access speeds are now measured in nanoseconds. That’s roughly the amount of time it takes light to travel ONE FOOT. (11.8 inches, 30 cm. Thank-you, Grace Hopper for the delightful illustration.)
Hard-drive access speeds are measured in milliseconds. That’s a million times slower than the RAM access time. That’s roughly the amount of time it takes light to travel 186 MILES!
Since inexpensive gigabyte RAM is the rule rather than the exception, it seems obvious to ask “How much memory is needed? Why do we permit applications to allocate endless resources? When should the OS say ‘no’ to an allocation request?” and the most obvious, “Why should anything in the OS be swapped to a storage medium with six orders of magnitude worse response time?”
Probably, the case can be made for a virtual server that swapping permits effective resource sharing. (Think mainframe again.) But on a standalone desktop system or physical server box, why swap? Define a minimum set of criteria for disabling the swap function, and redefine Windows’ paradigms. Let the users configure a system that will run efficiently with only available RAM, and not waste time chugging and thrashing the Hard Disk Drive.
Windows: Stop the swap, and start screaming again.
What does the TR community add to that?