On Tue, Nov 13, 2007 at 02:22:34PM -0800, Stephane Eranian wrote: > Andi, > On Tue, Nov 13, 2007 at 10:50:56PM +0100, Andi Kleen wrote: > > > Yes, horribly more complicated because of locking issues within perfmon. > > > As soon as you expose a file descriptor, you need some locking to prevent > > > multiple user threads (malicious or not) to compete to access the PMU > > > state. > > > > Why do you need the file descriptor? > > > > To identify your monitoring session be it system-wide (i.e., per-cpu) or > per-thread. > file descriptor allows you to use close, read, select, poll and you leverage > the
Surely that could be done with a flag for each call too? Keeping file descriptors to pass essentially a boolean seems overkill. > existing file descriptor sharing/inheritance sematics. At the kernel level, a > descriptor provides all the callback necessary to make sure you clean up the > perfmon > session state on exit. Didn't you already have a thread destructor for it? -Andi - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
