More questions....
---------- Forwarded message ---------- From: stephane eranian <[EMAIL PROTECTED]> Date: Tue, Dec 9, 2008 at 7:37 AM Subject: Re: [patch] Performance Counters for Linux, v2 To: Ingo Molnar <[EMAIL PROTECTED]> Cc: [EMAIL PROTECTED], Thomas Gleixner <[EMAIL PROTECTED]>, [EMAIL PROTECTED], Andrew Morton <[EMAIL PROTECTED]>, Eric Dumazet <[EMAIL PROTECTED]>, Robert Richter <[EMAIL PROTECTED]>, Arjan van de Veen <[EMAIL PROTECTED]>, Peter Anvin <[EMAIL PROTECTED]>, Peter Zijlstra <[EMAIL PROTECTED]>, Steven Rostedt <[EMAIL PROTECTED]>, David Miller <[EMAIL PROTECTED]>, Paul Mackerras <[EMAIL PROTECTED]> Hi, On Mon, Dec 8, 2008 at 2:22 AM, Ingo Molnar <[EMAIL PROTECTED]> wrote: > > > There's a new "counter group record" facility that is a straightforward > extension of the existing "irq record" notification type. This record > type can be set on a 'master' counter, and if the master counter triggers > an IRQ or an NMI, all the 'secondary' counters are read out atomically > and are put into the counter-group record. The result can then be read() > out by userspace via a single system call. (Based on extensive feedback > from Paul Mackerras and David Miller, thanks guys!) > That is unfortunately not generic enough.You need a bit more flexibility than master/secondaries, I am afraid. What tools want is to be able to express: - when event X overflows, record values of events J, K - when event Y overflows, record values of events Z, J I am not making this up. I know tools that do just that, i.e., that is collecting two distinct profiles in a single run. This is how, for instance, you can collect a flat profile and the call graph in one run, very much like gprof. When a you get a notification and you read out the sample, you'd like to know if which order values are returned. Given you do not expose counters, I would assume the only possibility would be return them in file descriptor order. But that assumes at the time you create the file descriptor for an event you have all the other file descriptors you need... > There's also more generic x86 support: all 4 generic PMCs of Nehalem / > Core i7 are supported - i've run 4 instances of KernelTop and they used > up four separate PMCs. > Core/Atom have 5 counters, Nehalem has 7. Why are you not using all of them already? ------------------------------------------------------------------------------ SF.Net email is Sponsored by MIX09, March 18-20, 2009 in Las Vegas, Nevada. The future of the web can't happen without you. Join us at MIX09 to help pave the way to the Next Web now. Learn more and register at http://ad.doubleclick.net/clk;208669438;13503038;i?http://2009.visitmix.com/ _______________________________________________ perfmon2-devel mailing list perfmon2-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/perfmon2-devel
