Page 1 of 1

RAM memory during render time

Posted: Tue Nov 25, 2008 11:00 am
by garbage75
Hi at all,
first of all sorry for my bad english!! :-)
I've got a 8 cores MACPRO and I use MR under OSX... i've got 8 GIGA of RAM and I'm wondering to increase till 16 GIGA..
so I know that MR using the RAM memory very hard during render start.. load file, export to MXS and voxelization... instead during the real render the processor is the most hardly used resource.
So I'd like to know if during the real render also the RAM is hardly used.. or only during the first step...
Does thing like poligon quantity, number of emitter, render resolution, multilight, can affect the RAM during render or only during the first step?
All this under OSX... not for Windows...
thanks at all friend
best

Posted: Tue Nov 25, 2008 1:53 pm
by Mattia Sullini
I am running similar hardware, and the RAM is the limit i have to deal with most often, since i run maxwell under OSX and not on the windows partition.
Checking the activity monitor when launching the render, can easily see that RAM usage grows fast during voxelization and other pèreliminary operation, but since when the render starts, usage does not decrease.
In facts, could happen that the render starts and then, after a couple minutes when MXCL tries to write on disk the .mxi and to update the preview, MXCL crashes.
At least, this is what happened in my personal experience! :D

Posted: Tue Nov 25, 2008 3:26 pm
by Mihai
Polygon count and number of emitters doesn't really pose a memory problem. Number of separate emitters matters only if you use multi light which will then increase the memory usage for each separate emitter you have in the scene. Ofcourse the render resolution will increase memory usage and the nr and resolution of textures, incl HDR maps that you use in the scene. You will see an initial increase in ram usage during voxelisation which will then drop (depending on how much geometry you have in the scene).

Posted: Tue Nov 25, 2008 3:34 pm
by garbage75
Mihai wrote:Polygon count and number of emitters doesn't really pose a memory problem. Number of separate emitters matters only if you use multi light which will then increase the memory usage for each separate emitter you have in the scene. Ofcourse the render resolution will increase memory usage and the nr and resolution of textures, incl HDR maps that you use in the scene. You will see an initial increase in ram usage during voxelisation which will then drop (depending on how much geometry you have in the scene).
sorry.. my english is bad than I could imagine.. so what you tell me is that for OSX, RAM usage initially increase depending on factor you told me, and then, once render start, the RAM usage decrease or to the limit it remains the same??

Posted: Tue Nov 25, 2008 4:32 pm
by Mihai
Yes :) It's the same for Windows/OSX. It has to load your bitmaps to RAM and also hold the multi light information during the render. So most influential for RAM usage: Resolution, bitmaps resolution, Multi light and nr of separate emitters (sliders in MXCL).

Posted: Tue Nov 25, 2008 4:45 pm
by garbage75
So we can say that the RAM usage is during the pre render till it start.. then after render start, the RAM usage could decrease or to the limit it remains the same??
there are some factor that could more or less hardly affect the RAM usage during the renders?

Posted: Tue Nov 25, 2008 5:09 pm
by Mihai
garbage75 wrote:So we can say that the RAM usage is during the pre render till it start.. then after render start, the RAM usage could decrease or to the limit it remains the same??
Exactly :)
there are some factor that could more or less hardly affect the RAM usage during the renders?
Not really, the ram usage will remain constant. At least I have never seen an instance where the ram usage could suddenly drop or increase during rendering.

Posted: Tue Nov 25, 2008 5:14 pm
by Mattia Sullini
Sorry Mihai if i dare to reply ( :D ), but i have never noticed any visible drop in RAM usage after voxelization...maybe it's because i usually render images with a lot of bitmaps and with multilight on, so that the polycount incides less?

Posted: Tue Nov 25, 2008 5:29 pm
by Mihai
Yes, it's certainly related to that. You will notice a drop after voxelisation if you have lots of heavy geometry but not so many huge textures.

Posted: Tue Nov 25, 2008 5:32 pm
by garbage75
Mihai wrote:Yes, it's certainly related to that. You will notice a drop after voxelisation if you have lots of heavy geometry but not so many huge textures.
could yo explain better this please??? :( my english it's so bad!!!

Posted: Tue Nov 25, 2008 8:38 pm
by Mattia Sullini
If you don't mind, Mihai, i will try to translate :)

Tra conterranei ci si deve aiutare! Quello che dice Mihai è che se hai un modello molto pesante in termini di geometria ma usato in una scena con poche luci e poche mappe, o con textures comunque piccole, dopo la fase preparatoria (voxelisation), la RAM impiegata diminuisce. Se invece il modello è relativamente leggero ma in scena hai molte luci o textures pesanti, allora questo calo si avvertirà meno perchè comunque il programma le deve tenere caricate in memoria.

Posted: Wed Nov 26, 2008 12:21 am
by Mihai
Grazie mille Mattia :D

Posted: Wed Nov 26, 2008 9:51 am
by garbage75
Grazie infinite Mattia and Mihai!!!! :D :D :D