How long does it take to allocate memory on the MIC?

I wrote some code to test the speed of allocating memory on the MIC. I find that allocte 4GB memory on MIC card need 
almost 14 seconds. Is this a normal speed?

The test program is like THIS:

  1 #include<stdio.h>
  2 #include<stdlib.h>
  3 void main(){
  4         int size=1024*1024*1024;
  5         __attribute__((target(mic:0)))float *a;
  6         a=(float*)malloc(size*sizeof(float));
  7 #pragma offload target(mic:0)nocopy(a:length(size) alloc_if(1) free_if(0))
  8  {}
  9 #pragma offload target(mic:0)nocopy(a:length(size) alloc_if(0) free_if(1))
 10  {}
 11 free(a);
 12 }

Then I got the OFFLOAD report:

[Offload] [MIC 0] [File]            test.c
[Offload] [MIC 0] [Line]            7
[Offload] [MIC 0] [Tag]             Tag 0
[Offload] [HOST]  [Tag 0] [CPU Time]        13.984358(seconds)
[Offload] [MIC 0] [Tag 0] [CPU->MIC Data]   0 (bytes)
[Offload] [MIC 0] [Tag 0] [MIC Time]        0.000158(seconds)
[Offload] [MIC 0] [Tag 0] [MIC->CPU Data]   8 (bytes)

[Offload] [MIC 0] [File]            test.c
[Offload] [MIC 0] [Line]            9
[Offload] [MIC 0] [Tag]             Tag 1
[Offload] [HOST]  [Tag 1] [CPU Time]        0.003295(seconds)
[Offload] [MIC 0] [Tag 1] [CPU->MIC Data]   16 (bytes)
[Offload] [MIC 0] [Tag 1] [MIC Time]        0.000047(seconds)
[Offload] [MIC 0] [Tag 1] [MIC->CPU Data]   0 (bytes)

I wonder if this test is right ? And allocating 4GB memory really need 14 seconds?