DAXPY's performacne is too low in LAPACK DTREVC routine while using multi-threads.

[lvjianchun]

In LAPACK DTREVC toutine, when using multi-threads, the performance is down to about 5% compare to single-thread.
when I replaced DAXPY by other BLAS' DAXPY(such as MKL, ATLAS), the performance is OK. I wonder if there's something wrong with daxpy.

[xianyi]

I wonder the workload is too small for axpy multi-threads version. Thus, the overhead of multi-threads costs a lot time.

Xianyi Zhang