On Thursday, July 21 at 16:53 (-0700), Grant said:
> So swap isn't treated exactly like RAM. It actually has special > handling in Linux which makes it beneficial to have on almost any > Linux system? According to Alan, things get very bad when a Linux > system hits swap. How can behavior like this be beneficial: > > "When a linux machine hits swap, it does so very aggressively, there > is nothing nice about it at all. The entire machine slows to a > painstaking crawl for easily a minute at a time while the kernel > writes pages out to disk, and disk is thousands of times slower than > RAM. > This is not entirely true. There's regular swapping and there is "thrashing". Thrashing is indicative of a memory-starved system, i.e. when many processes are trying to access memory, but there just isn't enough and the system is frantically swapping in/out. I'm talking about your normal day-to-day swapping that you probably don't even notice. > It gets so bad that you can't even run a shell properly to try and see > what's going on and kill the actual memory hog." Again, that is thrashing. I'm talking about "normal" swappage. Dont throw the baby out with the bath water. > Also, aren't you likely to wear out your hard disk sooner using swap? Is this coming from someone who uses Gentoo linux, which is constantly downloading/compiling/linking object files? Syslog and other loggers writing everything under the sun to a log file. Backups, journal writes, database transactions, etc. Compare how many disk transactions take place during your normal Gentoo usage versus a few megabytes here/there being swapped in/out. Again, I'm talking about regular swapping, not "oh my god I has no RAM and my hard drive won't stop" Even so, we're talking about modern drives here. This isn't the 1960s.
