Memory error in zgetrf_gpu

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Memory error in zgetrf_gpu

Postby jeremiahpalmer » Tue May 22, 2012 12:40 pm

Hello!

I was running magma_zgetrf_gpu (from magma_zgesv_gpu) and found a memory error. I am calling the routine magma_zgetrf_gpu with n=m=1024.

In line 107, nb is set to 32. In line 108, s is set to 32. Then, in line 219, we have

Code: Select all
       
lapackf77_zgetrf( &rows, &nb0, work, &lddwork, ipiv+s*nb, &iinfo);


The magma_int_t array "ipiv" is supposed to be length n. The above code segment will reference ipiv out of bounds.

-Jeremiah

P.S. This is in magma_1.1. So, if it is fixed in magma_1.2, I apologize!
jeremiahpalmer
 
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Re: Memory error in zgetrf_gpu

Postby Stan Tomov » Sun May 27, 2012 4:04 pm

I am trying to figure out if indeed there is a problem at this place because when min(m, n) is divisible by nb, as in this case, nb0 is actually zero, so the routine in question
Code: Select all
lapackf77_zgetrf( &rows, &nb0, work, &lddwork, ipiv+s*nb, &iinfo);

must exit with success without modifying any data. We could have executed this clean up code conditionally (when nb0 > 0) but we haven't seen a problems so far. It is possible though that an LU factorization implementation is not checking end exiting if n or m is zero. Did you indeed see a problem at this place and with what LAPACK implementation?
Thanks,
Stan
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Re: Memory error in zgetrf_gpu

Postby jeremiahpalmer » Sun May 27, 2012 5:56 pm

I ran magma_zgesv_gpu with the size 1024. The execution exited quite ungracefully. I traced the memory error using valgrind and found that it was failing at that particular line in magma_zgetrf_gpu. I printed the integer data s and nb just before lapackf77_zgetrf was called. It printed that both s and nb were 32.
-Jeremiah
jeremiahpalmer
 
Posts: 58
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Re: Memory error in zgetrf_gpu

Postby jeremiahpalmer » Tue Jun 12, 2012 12:08 pm

Any news on this error?

Thanks,
Jeremiah
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Posts: 58
Joined: Fri Jan 28, 2011 12:46 pm


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