> > So I definitely preffer 2 or 3 over 1. David has experience with 3. How well > does > it work for LIPO? >
This (lack of locking, races) is not a new problem. There is no synchronization in libgcov for profile update/merge at both thread and process level. Thread level data races leads to inconsistent counters, but can be mostly corrected under -fprofile-correction and smoothing. There is also problem with false indirect call targets --- gcc has mechanism to filter those out. Process level synchronization problems can happen when two processes (running the instrumented binary) exit at the same time. The updated/merged counters from one process may be overwritten by another process -- this is true for both counter data and summary data. Solution 3) does not introduce any new problems. thanks, David > Honza >> >> Thanks, >> Teresa >> >> > >> > Honza >> >> >> >> >> -- >> Teresa Johnson | Software Engineer | tejohn...@google.com | 408-460-2413
