Memory swap when there's apparently plenty of free RAM

[Eli Billauer]

Hi all,

I'm running FC12 with a 2.6.35.4 vanilla kernel on a x86_64.

When I opened Google Chrome last (I don't use it a lot), the computer 
froze completely for a minute, no mouse movement, no response to 
CTRL-Alt-F2, and the clock didn't change. The hard disk was highly 
active. After that minute, all resumed to normal, and the Chrome browser 
started as if nothing had just happened.

It then turned out that 2 GB of RAM had been swapped to disk.

My computer has 16 GB of RAM, out of which 9.7 GB were used at that 
moment. I have 4 GB of swap space allocated as a shock absorber, and 
it's normally around no more than a few MBs (why not just zero?).

I ran swapoff and swapon, and the used swap space now stands steadily at 
zero. Which is where I expect it to be.

Chrome is Version 19.0.1084.46, running natively in 64 bits (detected as 
64-bit ELF).

Any idea what happened? In particular, why triggered the swap for no 
apparent reason?

TAI,

     Eli

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Web: http://www.billauer.co.il