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]