Overall impression: nice! There have always been some pathalogical workloads that have confused the scheduler by executing synchronously with the timer tick ... this should end their tricks. A couple of comments: > + Select this option to enable more accurate task and CPU time > + accounting. This is done by reading a CPU counter on each > + kernel entry and exit and on transitions within the kernel > + between system, softirq and hardirq state, so there is a > + small performance impact. I haven't tried any macro-level benchmarks, but on a micro-benchmark to measure system call overhead I see an additional 19-20 cycles in the cached case. This doesn't look like a "small" performance impact (the execution time for a syscall in my benchmark is only ~61 cycles). But I'd like to see some real benchmarks to see whether the micro-level problem is measureable at the macro scale. One warning generated by this patch: kernel/posix-cpu-timers.c:41: warning: passing arg 1 of `timespec_to_cputime' discards qualifiers from pointer target type -Tony - To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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