William Kenworthy wrote:
On 21/07/13 22:31, luis jure wrote:
OK, now i have my system successfully installed and running on my new SSD.
now i have to decide what to do with the rest of the disk (it's a 256MB
samsung).
the first big question is: what about swap? i found some web pages
(perhaps old) stating that it's not wise to put swap on the SSD because of
all the read/writes. but apparently from what i read on the recent
thread on this list, that shouldn't be much of a concern now.
i also read somewhere that if you have swap on the SSD and want to avoid
unnecessary read/writes, you can reduce swappiness. i have 12GB RAM and i
think normally i don't really need swap space on disk, so i thought that
could be a good idea.
so what i'm planning to do now is:
- put swap on the SSD
- reduce swappiness
- put /var/tmp/portage on tmpfs
so, do you guys think that's a good setup?
swap: this will make one of the bigger speedups to the system when you
need swap. swap is good - yes you can do without it, but the day comes
when you REALLY do want it, and ... [crash!] ... otherwise it can just
sit there waiting :)
/etc/sysctl.conf:
#vm.swappiness=1
#vm.vfs_cache_pressure=50
these were recommended to me for running vm's and seem to do the job
(usually I am running with a several GB of swap (16G ram, 16G swap) in
use ... these settings definitely minimise it though big rsync jobs
stall when it fills ram+swap.
/var/tmp/portage is a more difficult one ... a long thread way back
(Dale, I think you were in it) looking at speed showed there was no
speed advantage to compiling in tempfs because spinner) disk caching was
so good the data only hit the disk when necessary. I presume the same
will apply with compiling and SSD's in that the actual writes will be
minimal (in the scheme of things) so it shouldn't be a worry. My
experience with compiling in tempfs is that it works, but has a much
higher failure rate than on disk - i.e., things like OO/Lo, KDE, gcc and
glibc have large space requirements that you must make sure tmpfs can
satisfy before you start. And if its a busy machine actively using lots
of ram it gets "hard". I am making the point that most machines today
are way overprovisioned but when you are near the edge, saying things
like I gave xGB ram and never needed swap, so you wont either is
misrepresenting the situation.
BillK
Yes, I did so some testing on whether portage's work directory on tmpfs
instead of HDD was faster or not and it wasn't much difference. I
actually had a couple times where it was faster on HDD but could have
been that some other process took up a few seconds of time too. The
difference was literally seconds on compiles that were between 30
minutes to one hour.
Dale
:-) :-)
--
I am only responsible for what I said ... Not for what you understood or how
you interpreted my words!
