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imation铁杆木虫 (正式写手)
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[交流]
castep多核运算的问题
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大家好，我有一台服务器，cpu为至强clovertown双路四核，每个核心频率是2ghz，内存667，4条，单条1g，操作系统装过2003中文版，sp1和sp2，也装过英文版sp1，2008英文版sp1 我尝试着运行tutorial里面的co分子adsorption在pb表面，一个核心运行很正常，1个小时就有结果，可是8个核心就总是失败，出现的问题也是千奇百怪： 1）进程castep，共八个，可是运行一会儿以后，自动减少到5个，有一次甚至减少到1个，内存无释放，有时任务失败，有时一直运算，但结果遥遥无期 2）cpu利用率在开始计算时为满负荷，经过1到5分钟，降到1~3%，内存没有释放，过10分钟左右，任务失败 3）尝试改变核心数目，发现1到3个都可以正常运行得到结果，超过3个就失败 4）还有n多错误，其中出现最多一个（每次都是在第一个点时出现），代码如下： *Warning* max. SCF cycles performed but system has not reached the groundstate. Current total energy, E = -5951.893478460 eV Current free energy (E-TS) = -5951.990514506 eV (energies not corrected for finite basis set) NB est. 0K energy (E-0.5TS) = -5951.941996483 eV **************************************************************************** Warning: electronic minimisation did not converge when finding ground state. **************************************************************************** Writing model to 1.check Error in geom_get_forces - electronic_minimisation of current_cell failed Error in geom_get_forces - electronic_minimisation of current_cell failed Error in geom_get_forces - electronic_minimisation of current_cell failed Error in geom_get_forces - electronic_minimisation of current_cell failed [1] MPI Abort by user Aborting program ! [1] Aborting program! [2] MPI Abort by user Aborting program ! [2] Aborting program! [0] MPI Abort by user Aborting program ! [0] Aborting program! forrtl: severe (47): write to READONLY file, unit 60, file D:\PROGRA~1\Accelrys\MATERI~1.1\Gateway\root_default\dsd\jobs\4GLA1\killfile Image PC Routine Line Source castepexe_mpi.exe 00AB6CC2 Unknown Unknown Unknown castepexe_mpi.exe 00AB3F50 Unknown Unknown Unknown castepexe_mpi.exe 00A42B9E Unknown Unknown Unknown castepexe_mpi.exe 00A427BB Unknown Unknown Unknown castepexe_mpi.exe 00A246D1 Unknown Unknown Unknown castepexe_mpi.exe 009F8E7B Unknown Unknown Unknown castepexe_mpi.exe 009F8EAF Unknown Unknown Unknown castepexe_mpi.exe 004FB352 Unknown Unknown Unknown castepexe_mpi.exe 004E5281 Unknown Unknown Unknown castepexe_mpi.exe 004DC8D0 Unknown Unknown Unknown castepexe_mpi.exe 00402353 Unknown Unknown Unknown castepexe_mpi.exe 00ABE578 Unknown Unknown Unknown castepexe_mpi.exe 00A904BB Unknown Unknown Unknown kernel32.dll 7C82F23B Unknown Unknown Unknown 我尝试增加maximum iterations到1000，Max SCF cycles到5000，八核并行运算，算了2天半，正常，我stop运算，在输出中发现还是有些错误： WARNING - user ionic constraints and symmetry specified - symmetry has precedence over constraints - may lead to a conflict? HINT - if convergence fails try switching symmetry OFF BFGS: Warning - trial step suggests complex energy landscape in which simple line minimization will fail. - This is usually an indication that the forces/streses are not accurate enough. Consider increasing the cutoff energy and/or the electronic convergence tolerance. - Proceeding with a bisection search to find root instead. Warning: There are no empty bands for at least one kpoint and spin; this may slow the convergence and/or lead to an inaccurate groundstate. If this warning persists, you should consider increasing nextra_bands and/or reducing smearing_width in the param file. Recommend using nextra_bands of 14 to 29. BFGS: Warning - Repeated consecutive reset of inverse Hessian BFGS: without satisfying convergence criteria which BFGS: looks like BFGS has run out of search directions. BFGS: Warning - Lets try allowing some uphill steps and see if BFGS: we can get around this barrier. BFGS: Warning - It is possible that the system may now converge to BFGS: a stationary point OTHER than the desired minimum. BFGS: Hint - this may be an indication that either: BFGS: a) you are using a poor guess at geom_frequency_est BFGS: and/or geom_modulus_est, or BFGS: b) you are using unrealistic convergence criteria. BFGS: Suggest therefore that you consider changing them! 等等，就不一一列出了 我的问题是，为何单核1个小时就能算出来的project，多核要么不能运算，要么运算起来比单核还要慢得多？是不是多核并行处理的时候数据交换有问题啊？ 谢谢，不知道描叙清楚了没有  |
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imation
铁杆木虫 (正式写手)
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3楼2007-12-07 22:26:34
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csfn(金币+2,VIP+0):感谢积极的交流 :-) 欢迎常来
csfn(金币+2,VIP+0):感谢积极的交流 :-) 欢迎常来
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多个cpu运行的话，容易出错。只要其中一个进程出错，计算就不会有结果 此时其他进程仍在运行，这可能就是为什么1个cpu1个小时算完，多cpu运行算很久没有结果的原因。 另外，在多个cpu运行过程中，上面还有很多warning信息 1。HINT - if convergence fails try switching symmetry OFF 这里可能是限制对称性，导致不好收敛，或者给原子设置了constrain，有时候收敛困难，可以在计算的时候去掉symmetry，试试看。 2。BFGS: Warning - trial step suggests complex energy landscape in which simple line minimization will fail. 平面波cutoff设置可能过小。 3。empty band空带数不足，如果体系是金属性的话，不容易收敛。 |
2楼2007-12-07 21:25:38
cometring
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4楼2007-12-08 14:48:52
6楼2008-10-19 00:23:30
