[arch-general] What dirs are good to put in a tmpfs?

[Leonid Isaev]

On Wed, 24 Jul 2013 21:27:11 -0600
Chris Moline <blackredtree at gmail.com> wrote:

> Hi, I have 7 GiB of ram but I'm only using 300 MiB, so I thought I
> would put stuff into it to speed up my system.

A great way to utilize RAM is to run several VMs :) Also I wonder what is your
chipset/RAM type, because on a typical desktop board with modern CPU and RAM
modules, your memory size should be even for the optimal (dual-channel)
performance. Or is your video memory shared?

> I installed
> anything-sync-daemon but I have no idea what to sync. Is there a tool
> that can tell which dirs are being used the most? I'd rather not guess
> and benchmark, I don't have the patience for that. What are common
> dirs that would benefit from being in ram?

It all depends on your usage pattern.

One procedure which really benefits from being done in RAM is building
packages, especially large ones like gcc, glibc or qemu.

In some circumstances, you'd want to store systemd journal and/or part of
syslog log files in RAM. For example, HostAP (wireless authentication) daemon
can log a lot. As a result, the journal grows dozens of MiB a day which
quickly makes reading it off the disk rather painful. Since the journal cannot
be fine tuned, I usually configure it to be volatile, and also tell syslog to
write hostapd-related messages to e.g. /tmp/log/hostapd.log.

For a regular desktop, people put in RAM ~/.mozilla, ~/.local/chromium (or
whatever Chrome uses these days), etc. However, in my experience the resulting
speedup is next to none and not worth the risk of data loss in case of a power
failure or a system freeze... The truth is that on desktop machine which does
not do virtualization, you don't need more than 2GiB or RAM. Remember, memory
modules do consume power so it may be sensible to remove most of them.

Cheers,
-- 
Leonid Isaev
GnuPG key: 0x164B5A6D
Fingerprint: C0DF 20D0 C075 C3F1 E1BE  775A A7AE F6CB 164B 5A6D
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