[mistwang]

Originally Posted by Tony

We played around with eaccelerator a bit on one machine but for the density of our machines it's not even worth doing. We actually had higher i/o wait due to the amount of cached files it ended up writing. I think in the end we had about 12GB of cached files eccelerator does have a memory only feature but I did not see any real improvements. I'm guessing it has to do with the timeout of the PHP processes and such.

Yes, that's true that it will cause high I/O wait if you use /tmp/eaccelerator/ as the storage. However, using /dev/shm/ is more like using a memory disk, which is lightening fast without increasing I/O wait.