Using an SSD "disk" for /

[Oliver Fromme]

Jeremy Chadwick wrote:
 > As for the performance: it's something you'll have to see for yourself.
 > The performance is outright amazing when it comes to administrative
 > tasks (OS installation, newfs, massive copies of data to/from the SSD,
 > updating /usr/src and /usr/ports, etc.).  Try a build/install world or
 > kernel sometime on an SSD and watch your terminal.  You'll be pretty
 > impressed.

What kind of tuning do you apply to those file systems?

I'm asking because I can't really reproduce those results.
On a machine with plenty of RAM I've created memory disks
for obj and src, which should at least be as fast (probably
even faster) than an SSD.  Buildworld was somewhat faster,
compared to standard (well-tuned) UFS+SU filesystems on a
fast SATA HDD, but not _that_ much faster.  In fact the
difference was small enough that I stopped using memory
disks and returned to using UFS+SU+noatime (and a few other
tuning options) on a HDD.

So, if you experience a _dramatic_ speed-up when using SSDs
for buildworld, I would really very much like to know why
this is the case, and what kind of tuning you performed.

Best regards
   Oliver

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