Recent impressive performance improvements in computer architecture have not led to significant gains in the case of debugging. Software debugging often relies on inserting run-time software checks. In many cases, however, it is hard to find the root cause of a bug. Moreover, program execution typically slows down significantly, often by 10—100 times. To address this problem, this paper introduces the intelligent watcher (iWatcher), a novel architectural scheme to monitor dynamic execution automatically, flexibly, and with minimal overhead. iWatcher associates program-specified monitoring functions with memory locations. When any such location is accessed, the monitoring function is automatically triggered with low overhead. To further reduce overhead and support rollback, iWatcher can optionally leverage thread-level speculation (TLS). The iWatcher architecture can be used to detect various bugs, including buffer overflow, accessing freed locations, memory leaks, stack-smashing and value-invariant violations. To evaluate iWatcher, we use seven applications with various real and injected bugs. Our results show that iWatcher detects many more software bugs than Valgrind, a well-known open-source bug detector. Moreover, iWatcher only induces a 0.1—179% execution overhead, which is orders of magnitude less than Valgrind. Our sensitivity study shows that even with 20% of the dynamic loads monitored in a program, iWatcher adds only 72—182% overhead. Finally, TLS is effective at reducing overheads for programs with substantial monitoring.
|Original language||English (US)|
|Number of pages||31|
|Journal||ACM Transactions on Architecture and Code Optimization|
|State||Published - 2005|
ASJC Scopus subject areas
- Information Systems
- Hardware and Architecture