What does “Page faults with physical i/o: 4897\ mean?
This question was asked on the squid-users mailing list, to which there were three excellent replies. by Jonathan Larmour You get a “page fault” when your OS tries to access something in memory which is actually swapped to disk. The term “page fault” while correct at the kernel and CPU level, is a bit deceptive to a user, as there’s no actual error – this is a normal feature of operation. Also, this doesn’t necessarily mean your squid is swapping by that much. Most operating systems also implement paging for executables, so that only sections of the executable which are actually used are read from disk into memory. Also, whenever squid needs more memory, the fact that the memory was allocated will show up in the page faults. However, if the number of faults is unusually high, and getting bigger, this could mean that squid is swapping. Another way to verify this is using a program called “vmstat” which is found on most UNIX platforms.
