zswap – compcache, compressed swap for better performance

First, here is a link to article on compcache.

http://code.google.com/p/compcache/wiki/CompilingAndUsingNew

zswap is already in the kernel and you can see the documentation in the kernel documentation. Here is the name of the file if you need:

/usr/share/doc/kernel-doc-$(uname -r)/Documentation/vm/zswap.txt

Here is the overview, in case you do not want to install kernel-doc

Overview:

Zswap is a lightweight compressed cache for swap pages. It takes pages that are
in the process of being swapped out and attempts to compress them into a
dynamically allocated RAM-based memory pool.  zswap basically trades CPU cycles
for potentially reduced swap I/O.  This trade-off can also result in a
significant performance improvement if reads from the compressed cache are
faster than reads from a swap device.

Continue reading

vmstat – what it is and how to use?

vmstat provides a summary of various functions within the system, including system wide free memory, paging counters, summarized disk activity, system calls and cpu utilization.

The output of vmstat and description of what each field means:

The first line of output from vmstat shows a summary since boot,
followed by the output over the last 3 seconds for each additional line.