There is much more to write about all the work we do at Facebook with memory management efficiency on our systems, but there was this one detour investigation in the middle of 2012 that I had to revisit recently courtesy of Wikipedia.
There are lots of factors that make machines page out memory segments into disk, thus slowing everything down and locking software up – from file system cache pressure to runaway memory leaks to kernel drivers being greedy. But certain swap-out scenarios are confusing – systems seem to have lots of memory available, with proper settings file system cache should not cause swapping, and obviously in production environment all the memory leaks are ironed out.
And yet in mid-2012 we noticed that our new kernel machines were swapping out for no obvious reason. When it comes to swapping, MySQL community will always point to Jeremy’s post on[Read more...]