A few comments:

a. The patch basically spawn a new process to handle the additional "xm" inputs asynchronously. Correct? And since currently this is not possible, it also means that the possibilities of deadlocks or race conditions through concurrent access to xend via different xm users is not thoroughly verified. Correct? May be. So this is something to look out for.

b. The performance of dump core is slow, mainly because external hard disk are slow. Therefore, there could be four different options/variations: minidump vs full-dump. For each there could be a compressed vs no-compression option - compressed is to get a smaller physical core.

c. Furthermore, there could be an additional throttling parameters to specify how much to slow the coredump operation, for example, by forcing a CPU re-scheduling operation (higher overheads in task switching - tradeoff for responsiveness) after every fix number of blocks. This will also have the effect of improving performance for additional domU's operation.

Thank you very much.