Hi,
  I am trying ac simulation using "corner" tool and it says "insufficient memory".
  If I use "corner" tool for just one corner simulation, it is Ok. And I look at the memory. This simulation takes just 3.5% of all the memory.
  If I'm using "corner" tool for more than one corner simulation. The first corner ac simulation is going well but the second one starts and simulates for a long time (I think it might be calculating dc operating point) until it runs out of memory. The output log stops at the message below and then prints "insufficient memory".

********************************************
AC Analysis `ac': freq = (-80 MHz -> 80 MHz)
********************************************

  So I'm cofused about the "corner" tool. Definitely I can run corner simuation one by one, but it is troublesome. Here is the circuit inventory. Is there some suggestion? Thank you for that.

            nodes 36327
         equations 78448
            iprobe 6    
    ahdl simulator 1    
           bsim3v3 19920
         bsource_1 1120  
        bsource_33 17744
        bsource_98 8872  
           isource 10    
              port 2    
          quantity 9    
          resistor 102  
              vcvs 6    
           vsource 23

Thank you, Andrew.
I monitor the memory usage in simulation. It is not like PSS. In PSS simulation, you can see the memory usage grows very fast to 4Gb limit in around 5 minutes. This has nothing to do with "corner" tool because it is so in normal simulation. Moreover, I have the option of "swap file".
But this one is special. In corner simulation, it takes only 6 minutes for the first corner simulation to take up 3.5% of memory and finish,  but more than 60 minutes for the second simulation to compute until it takes up all the memory. In normal simulation, it is quite like the first corner simulation. There might be some problems with "corner" tool.

Hi, Andrew,
 Thanks for your reply. My icfb version is 5.10.41. I actually don't understand the mechanism of corner tools.
 I have seen two typical cases of corner tool.
1)
In CIW window, there is something like"
Delete psf data in /home/wangrui/simulation/filter_spmod_tb/spectreVerilog/config/psf.
  ... Corner simulation #15/25 finished with status=ok, corner="slow_hot2" ...
Delete psf data in /home/wangrui/simulation/filter_spmod_tb/spectreVerilog/config/psf.
  ... Corner simulation #16/25 finished with status=ok, corner="typ3" ...
"
The output log looks like a normal simulation.
but refreshing itself after a new corner begins.

2)
nothing in CIW window.
The output log has something like
"
***********************
Alter Group `fast_best'
***********************
       device "I453.I496.M123.m0" is altered
       device "I453.I496.M124.m0" is altered
       device "I453.I496.M132_1.m0" is altered
       device "I453.I496.M132_2.m0" is altered
       device "I453.I496.M132_3.m0" is altered
       device "I453.I496.M18.m0" is altered
       .......
"
The first one is very robust but the second one is prone to failure,.

My simulation output used to be like case 2. It refuses to work and that's why I posted here for help. Then I deleted some variables and used a even larger circuit, the simluation looks like case1 and it works. But I am still confused.

Andrew,
  I came across case 2 recently and I called the function as you told me and the output became case 1. Amazing!  :)
  Thank you!

Ray