On 10/01/14 07:27, Bernd Edlinger wrote:
Hi Jeff,as you know, this test case takes too long to complete if the test suite is run with this command line: MALLOC_PERTURB_=237 make -k check The reason was found in libcpp/charset.c, where a reallocation is done one byte at a time. It seems to be in the macro expansion of this construct: #define t16(x) x x x x x x x x x x x x x x x x #define M (sizeof (t16(t16(t16(t16(t16(" ")))))) - 1) libcpp is calling realloc 1.000.000 times for this, resizing the memory by just one byte at a time. And the worst case of realloc is O(n), so in the worst case realloc would have to copy 1/2 * 1.000.000^2 bytes = 500 GB of memory. With the change that you suggested, we increase the memory allocation by 25%, and now the complete test suite gives exactly the same results with or wihout MALLOC_PERTURB_ . Boot-strapped and regression-tested with and without MALLOC_PERTURB_ Ok for the trunk? Thanks, Bernd. patch-libcpp.diff 2014-10-01 Bernd Edlinger<bernd.edlin...@hotmail.de> Jeff Law<l...@redhat.com> * charset.c (convert_no_conversion): Reallocate memory with 25% headroom.
OK. Jeff
