Re: [PLUG] Solved! What Files Are Open Over Time?

[Rich Freeman <r-plug@thefreemanclan.net>]

On Mon, Dec 12, 2011 at 8:31 PM, Casey Bralla <MailList@nerdworld.org> wrote:
> I store all my "data" files on an NFS network file server, so I have no
> intention of putting that stuff on an SSD. Although I run Gentoo "~AMD64"
> (ie: Unstable) and compile things all the time, I don't see the point of
> spending a $100+ for a good SSD just to speed up compile times. (About half
> my compile times seem to be disk I/O)

In almost all cases mount /var/tmp as a tmpfs on gentoo will GREATLY
improve your compile times.  If you have spare RAM then all the
intermediate files will never hit the disk at all.  Nothing can
eliminate the need to write the new files to your normal filesystem
(that is true of any package management system).

I have 8GB of RAM and I usually don't see that get used up even
building with make -j5 and emerge --jobs=4 - that is potentially 20
gcc instances running at a time though in reality it is rare to take
advantage of that.  Even if you start running low on RAM in theory the
tmpfs dumping /some/ stuff to disk is no worse than a regular
filesystem dumping /everything/ to disk.

Also - atop is a VERY useful program for this sort of thing if you
have accounting turned on in your kernel.  It can show you all the
stats of top/iotop/etc, except it can show you them since boot whether
the program has been running or not.  It also shows you activity over
10 second intervals rather than snapshots - which catches a lot of
stuff that launches and terminates quickly.  It is available as a
package on gentoo and I'm sure it ewarns you about the necessary
kernel options if they aren't set.

Rich
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