> AIX basically did this with SIGDANGER (the signal is ignored by > default), except there wasn't the ability for the process to tell the > kernel at what level of memory pressure before it should start getting > notified, and there was no way for the kernel to tell how bad the > memory pressure actually was. On the other hand, it was a relatively > simple design. AIX does provide a system call to find out how much paging backing store space is available and the thresholds set by the system administrator. Running out of paging space is the only memory pressure AIX is concerned about. While I think having processes make memory usage decisions based on that is a shoddy way to manage system resources, that's what it is intended for. Incidentally, some context for the AIX approach to the OOM problem: a process may exclude itself from OOM vulnerability altogether. It places itself in "early allocation" mode, which means at the time it creates virtual memory, it reserves enough backing store for the worst case. The memory manager does not send such a process the SIGDANGER signal or terminate it when it runs out of paging space. Before c. 2000, this was the only mode. Now the default is late allocation mode, which is similar to Linux. -- Bryan Henderson IBM Almaden Research Center San Jose CA Filesystems - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
