[Users] Probable speedup of simulations - Ram File system
knarf at cct.lsu.edu
Tue Dec 25 00:46:52 CST 2012
Thanks for your suggestion. In short: I wouldn't expect anyone here
having tried this, but I believe it would work. Assuming the data fits
into ram that is. Often that "if" is too big.
A longer answer:
On Mon, Dec 24, 2012 at 01:52:47PM -0600, David N. Bradley wrote:
> After compiling the cactus and ET, I ran the static_tov simulation in
> a ram file system. It seems to run faster, since it did not have to
> spin up the harddrive for each iteration and append the data.
Does your hard drive really spin up and down between data writes? Well -
in case it really does I imagine that yes, in that case a ram file
system could help in some cases.
However, I have to say that most, if not almost all Cactus users run
on machines with disks that never sleep. On production clusters the
file system you are writing to is a network file system most of the time
anyway (again, with either disks that spin all the time anyway or SSDs
Now on the other extreme you have laptop systems. Running a simulation
on battery for a long time is a bad idea anyway, so I assume you are
plugged in. Especially then I wouldn't let the disk spin down at all as
long as you are working on it. It just creates lags and wears the disk
more than letting it spin idle. Personally I don't let it spin down
even on battery, but that is personal preference (When on battery I am
on the machine, working. When I work I do write to disk quite often.
Spinning a disk up needs time and power - so I don't bother letting it
spin down in the first place.)
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