I've created instructions on building v8 and running a molecular dynamics engine we are working on with various profiling flags turned on:
https://gist.github.com/2289269 I'm working to understand the serious performance regression in Chrome I reported here: Huge performance regression/variation in Chrome after changing window size and reloading (using typed arrays and SVG) http://code.google.com/p/chromium/issues/detail?id=121196 I do not yet know if the data I am collecting also shows the kind of slowdowns we are seeing in Chrome -- but is it already clear that something is causing the main integration function to be deoptimized over and over: makeIntegrator.integrate() See the profile.log here: https://raw.github.com/gist/2289269/profiling.log I've been reading Florian Loitsch's series on profiling and optimizing code for V8 starting with this post: http://floitsch.blogspot.com/2012/03/optimizing-for-v8-introduction.html But I'm still trying to understand what is causing the deoptimization ... the deoptimization of makeIntegrator.integrate() makes the code run much slower than it needs to. I'm getting a series of reports like these: **** DEOPT: makeIntegrator.integrate at bailout #436, address 0x0, frame size 1004 ;;; @2986: check-maps. [deoptimizing: begin 0x2b41155d makeIntegrator.integrate @436] translating makeIntegrator.integrate => node=1794, height=112 ... **** DEOPT: makeIntegrator.integrate at bailout #213, address 0x0, frame size 984 ;;; @1546: deoptimize. [deoptimizing: begin 0x2b41155d makeIntegrator.integrate @213] translating makeIntegrator.integrate => node=853, height=132 Is there more documentation for understanding results like: ;;; @2986: check-maps and ;;; @1546: deoptimize I do not yet have good profile data to make any definitive interpretation of the following results .. but I am normally seeing the model itself running at 550-600 model-steps/s (Mac OS X 10.6.8, 2.66 GHz Intel Core i7, w/8GB memory). When Chrome is running slowly the rate drops to 120-150 ... however during one test on Windows 7 (on the same machine) I got a measurement of 1724 model-steps/s. It would be nice to get that performance more regularly. FYI: you can see the model run with a visualization of molecular dynamics here: http://concord-consortium.github.com/lab/examples/simple-atoms-model/simple-atoms-model.html -- v8-users mailing list [email protected] http://groups.google.com/group/v8-users
