diff options
| author | James Slocum <j.m.slocum@gmail.com> | 2013-10-03 21:16:39 -0400 |
|---|---|---|
| committer | James Slocum <j.m.slocum@gmail.com> | 2013-10-03 21:16:39 -0400 |
| commit | bf194646e7a4bd348fd6033b183a1fd78a0aaef1 (patch) | |
| tree | fe51dfa05dcfc91f56577eb08a85785d9a931466 | |
| parent | 93a74f64ce6e30e940ebbf456bf35679bca8d668 (diff) | |
Fixed 2 bugs.
Fixed a segfault, and read error.
1) the for(t=0; t<array_size; t+=block_size) loop could write past the end of the buffer and segfault
2) The 'a' buffer was not being advanced, causing the same memory to be read over and over, this caused heavy cache hits and unrealistically high results.
| -rw-r--r-- | README | 1 | ||||
| -rw-r--r-- | mbw.c | 9 |
2 files changed, 7 insertions, 3 deletions
@@ -1,6 +1,7 @@ MBW determines the "copy" memory bandwidth available to userspace programs. Its simplistic approach models that of real applications. It is not tuned to extremes and it is not aware of hardware architecture, just like your average software package. 2006, 2012 Andras.Horvath atnospam gmail.com +2013 j.m.slocum atnospam gmail.com http://github.com/raas/mbw @@ -27,6 +27,8 @@ * MBW memory bandwidth benchmark * * 2006, 2012 Andras.Horvath@gmail.com + * 2013 j.m.slocum@gmail.com + * (Special thanks to Stephen Pasich) * * http://github.com/raas/mbw * @@ -97,6 +99,7 @@ double worker(unsigned long long asize, long *a, long *b, int type, unsigned lon unsigned int long_size=sizeof(long); /* array size in bytes */ unsigned long long array_bytes=asize*long_size; + unsigned int advance=block_size/long_size; if(type==1) { /* memcpy test */ /* timer starts */ @@ -106,11 +109,11 @@ double worker(unsigned long long asize, long *a, long *b, int type, unsigned lon gettimeofday(&endtime, NULL); } else if(type==2) { /* memcpy block test */ gettimeofday(&starttime, NULL); - for(t=0; t<array_bytes; t+=block_size) { + for (t=array_bytes; t >= block_size; t-=block_size, a+=advance){ b=mempcpy(b, a, block_size); } - if(t>array_bytes) { - b=mempcpy(b, a, t-array_bytes); + if(t) { + b=mempcpy(b, a, t); } gettimeofday(&endtime, NULL); } else { /* dumb test */ |