4 ms·

How does this compare to Chrome?

mtgx 14y ago
Firefox stable is version 15, Chrome is 21. Since they both use a 6 week release, and Mozilla is introducing this in Firefox 18, that means it should be compared to Chrome 24 or Chrome 25, depending on which is released first.
kevingadd 14y ago
In my experience at present, comparing Chrome Canary with Firefox Nightly, SpiderMonkey and V8 both win on particular use cases now (sometimes quite dramatically). V8 tends to win on stuff that depends on garbage collection since they have a generational collector, and SpiderMonkey only has incremental. SpiderMonkey wins on some computation workloads because V8 still has a huge limitation where they often have to store floats as individual allocations on the heap (that's the best explanation I can come up with, at least; impossible to tell for sure from the Chrome profiler) V8 also wins on some use cases that make use of new ES5 features like Object.defineProperty, because their optimizations do a better job with them. IonMonkey is definitely a big improvement over the previous generation of SpiderMonkey, though. They're closing the gap. P.S. It's a little hard to measure this stuff because V8 has some optimizations that happen to be perfect for benchmarks but provide a much smaller win for applications (Loop invariant code motion, for one). Nothing naughty going on here, you just need to be aware the numbers are lies.
- dochtman 14y ago
  SpiderMonkey should hopefully get a generational GC soonish: https://bugzilla.mozilla.org/show_bug.cgi?id=619558 https://bugzilla.mozilla.org/show_bug.cgi?id=619558. (Incremental GC was completed recently, for Fx 16: https://bugzilla.mozilla.org/show_bug.cgi?id=641025. https://bugzilla.mozilla.org/show_bug.cgi?id=641025.)
- magicalist 14y ago
  IonMonkey does loop invariant code motion as well, and of course it's not "naughty", that's a widely used and standard compilation technique. It's also exactly what you want: there are many instances when keeping an invariant statement inside a loop results in clearer code, and there's no reason you should have to realize that and make your code more awkward and less maintainable when it's something the compiler can handle easily. What it sounds like you're describing is that people are still writing terrible benchmarks. The days of this sort of thing on jsperf being useful are numbered: function benchmark() { for (var i = 0; i < 1000000; i++) { var result = computationWithNoSideEffects(); } } Yes, a good compiler will turn that into a noop. And no, that's not being naughty either. It's just a terrible benchmark. (also, when using crankshaft, doubles in V8 are unboxed and not allocated on the heap).
- mraleph 14y ago
  > SpiderMonkey wins on some computation workloads If the difference is huge then it'll be appreciated if you take those workloads and file bugs based on them.
- sebilasse 14y ago
  I've been benchmarking various methods recently and also figured out that optimizations basically make it impossible (or very hard) to benchmark correctly. Are there any resources about these optimizations?
azakai 14y ago
It depends on the benchmark. Each of the major browsers - Chrome, IE, Firefox, Safari, Opera - have benchmarks that they beat the competition at. Competition has made all of them very fast.

mtgx 14y ago

Firefox stable is version 15, Chrome is 21. Since they both use a 6 week release, and Mozilla is introducing this in Firefox 18, that means it should be compared to Chrome 24 or Chrome 25, depending on which is released first.

kevingadd 14y ago

In my experience at present, comparing Chrome Canary with Firefox Nightly, SpiderMonkey and V8 both win on particular use cases now (sometimes quite dramatically). V8 tends to win on stuff that depends on garbage collection since they have a generational collector, and SpiderMonkey only has incremental. SpiderMonkey wins on some computation workloads because V8 still has a huge limitation where they often have to store floats as individual allocations on the heap (that's the best explanation I can come up with, at least; impossible to tell for sure from the Chrome profiler) V8 also wins on some use cases that make use of new ES5 features like Object.defineProperty, because their optimizations do a better job with them. IonMonkey is definitely a big improvement over the previous generation of SpiderMonkey, though. They're closing the gap. P.S. It's a little hard to measure this stuff because V8 has some optimizations that happen to be perfect for benchmarks but provide a much smaller win for applications (Loop invariant code motion, for one). Nothing naughty going on here, you just need to be aware the numbers are lies.

dochtman 14y ago
SpiderMonkey should hopefully get a generational GC soonish: https://bugzilla.mozilla.org/show_bug.cgi?id=619558 https://bugzilla.mozilla.org/show_bug.cgi?id=619558. (Incremental GC was completed recently, for Fx 16: https://bugzilla.mozilla.org/show_bug.cgi?id=641025. https://bugzilla.mozilla.org/show_bug.cgi?id=641025.)
magicalist 14y ago
IonMonkey does loop invariant code motion as well, and of course it's not "naughty", that's a widely used and standard compilation technique. It's also exactly what you want: there are many instances when keeping an invariant statement inside a loop results in clearer code, and there's no reason you should have to realize that and make your code more awkward and less maintainable when it's something the compiler can handle easily. What it sounds like you're describing is that people are still writing terrible benchmarks. The days of this sort of thing on jsperf being useful are numbered: function benchmark() { for (var i = 0; i < 1000000; i++) { var result = computationWithNoSideEffects(); } } Yes, a good compiler will turn that into a noop. And no, that's not being naughty either. It's just a terrible benchmark. (also, when using crankshaft, doubles in V8 are unboxed and not allocated on the heap).
mraleph 14y ago
> SpiderMonkey wins on some computation workloads If the difference is huge then it'll be appreciated if you take those workloads and file bugs based on them.
sebilasse 14y ago
I've been benchmarking various methods recently and also figured out that optimizations basically make it impossible (or very hard) to benchmark correctly. Are there any resources about these optimizations?

azakai 14y ago

It depends on the benchmark. Each of the major browsers - Chrome, IE, Firefox, Safari, Opera - have benchmarks that they beat the competition at. Competition has made all of them very fast.