Thanks eliot for your explanations. I will give it a try to SystemProfiler Thanks
On Tue, May 10, 2011 at 7:26 PM, Eliot Miranda <[email protected]>wrote: > > > On Sun, May 8, 2011 at 5:07 AM, Mariano Martinez Peck < > [email protected]> wrote: > >> >> >> What approach do you suggest should I take? >>>> >>> >>> I have no idea. You could try and break down the various activities and >>> benchmark them separately I suppose. You could look at the profiles you're >>> already generating in higher resolution to see where the time is going. You >>> could also try and extract the SystemProfiler from OpenQwaq, which will run >>> on Cog, and is better than MessageTally. Andreas wrote it to get around >>> some of MessageTally's limitations. It should hopefully show primitives >>> quite accurately. >>> >>> >> Hi. I have already read this several times. From you now, from Alexandre >> Bergel, from Henrik Johansen, etc. But no one (or maybe I didn't see it) >> give a list of the real existent MessageTally limitations or problems. So >> far, the only thing I read is what Eliot says here: "show primitives quite >> accurately" >> >> So...which are the rest and what is solved by the SystemProfiler from >> OpenQwaq ?? >> > > MessageTally works by using delays to cause a high-priority process to > interrupt the process being profiled. So the sample is taken only at a > suspension point. The SystemProfiler support in the VM takes a sample > either after a primitive has run or when the VM is checking for events, so > it takes more accurate samples. Further, the SystemProfiler's VM support > also samples the active process when collecting the sampled method, so it > more accurately ascribes profiles to processes. MessageTally only profiles > a single process. > > Both suffer from a bug my colleague Yaron Kashai observed this week at > Cadence, which is that if GC pauses are long then both profilers will > under-measure the GC costs because they both take a single sample before > measurement. So e.g. if a GC pause lasts five times longer than the poll > time only one sample will be takem. Ideally the SystemProfiler would be > extended to maintain a list of sampled methods and processes. > > > best, > Eliot > > >> Thanks in advance, >> >> >> Mariano >> >> >> >> >> >>> HTH >>> Eliot >>> >>> >>>> >>>> Cheers >>>> Philippe >>>> >>>> >>>> >>> >> >> >> -- >> Mariano >> http://marianopeck.wordpress.com >> >> > -- Mariano http://marianopeck.wordpress.com
