Performance enhancements

[Marvin P. Dickens]

On Mon, 30 Dec 2002 13:44:09 -0500
Tim Wunder <tim at thewunders.org> wrote:

> But, what could possibly be *gained*, performance-wise, by turning swap off? 
> If swap isn't needed, it won't be used...



Linux kernel code and data are not swappable and are never moved to
swap.  User code never needs to be written to swap space because it
already exists on disk and can be read in from there if it is required
again. User data is the only data that is written to swap space. Once user 
data is in swap, it is read back in when it is needed. If your application 
is dependent on swap performance, you need more RAM.  This is where you 
gain performance. Swap should be viewed as a lightweight background 
optimization to make unused pages available for other work, rather 
than as a cure for an underprovisioned machine (Which is what swap 
has become). The point was and still is that memory is dirt cheap (For 
the price of a crappy usb webcam, you can purchase 256MB of RAM).


Best

Peck