Author Topic: Xeon and Low ram  (Read 1765 times)

2016-11-16, 20:52:22

SHD

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I have got xeon with 32 gb ram (16gb+16gb).
In exterior scene i used a lot of proxy, when render is starting corona use not more than 24 gb but i've got corona error message - "system is running low on RAM" and etc.
What's wrong?

2016-11-17, 12:37:54
Reply #1

SairesArt

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The warning is based on percentage of System mem left and the percentage is not that low as far as I recall. (90% ?)

It says it in the message "You may experience..." If you do not encounter any other problems and if the scene still renders as fast as ever, than you can ignore it.
It serves as I reminder, that if you push onward and beyond your RAM amount, you will encounter paging, which will kill all performance.

However, do you happen to have dual Xeon? Is that what you mean by 16+16?
Then there are two modes for memory, SMP and NUMA. One allows to share memory and the other one doesn't. If it is in non share mode, than you only really have 16gb. I am not sure how this plays with Corona, as I have no idea how it works.

If you have performance drop, then state so and someone with dual xeon experience will have to answer this.
Prime User for questions like this is Juraj_Talcik, who is the moderator of the Hardware subforum.
If you have no performance drop, ignore the message and know, that you will soon reach the limit.

2016-11-17, 14:04:54
Reply #2

SHD

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The warning is based on percentage of System mem left and the percentage is not that low as far as I recall. (90% ?)

It says it in the message "You may experience..." If you do not encounter any other problems and if the scene still renders as fast as ever, than you can ignore it.
It serves as I reminder, that if you push onward and beyond your RAM amount, you will encounter paging, which will kill all performance.

However, do you happen to have dual Xeon? Is that what you mean by 16+16?
Then there are two modes for memory, SMP and NUMA. One allows to share memory and the other one doesn't. If it is in non share mode, than you only really have 16gb. I am not sure how this plays with Corona, as I have no idea how it works.

If you have performance drop, then state so and someone with dual xeon experience will have to answer this.
Prime User for questions like this is Juraj_Talcik, who is the moderator of the Hardware subforum.
If you have no performance drop, ignore the message and know, that you will soon reach the limit.

Interesting!
Yes, i have got dual xeon.

About SMP and NUMA - i try to check it a bit later.
Another moment that sometimes i have BSOD or reboot of my system (even pc doesn't render).

SairesArt - Thank you!

2016-11-21, 14:54:35
Reply #3

Ryuu

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The SMP and NUMA modes should only affect how the memory is mapped to the CPU address space. In both modes all the memory is accessible, but in NUMA mode you may see negative performance impact for non NUMA-aware applications (like Corona).

Windows task manager may be a bit deceiving in reporting the memory usage. The memory allocation actually works in a way that the application requests some memory and system reserves an address range for that memory, but the actual physical memory is allocated for the application only after it is accessed for the first time (and only then it is actually allocated in 4 KB chunks). So it may happen that the application requests 1 MB of memory and then actually uses only 64 KB and this is the value that is reported in the task manager.

This warning is displayed when Corona receives a low system memory notification event from the OS. Right now I can't find any info about what exactly classifies as low memory state.