559237 - analyze L2 cache behavior

Status: NEW

(Core :: JavaScript Engine, task, P3)

Description

[Andreas Gal :gal]

We should do this for every SS and V8 test. There is some very obvious stuff lurking here (example string-unpack-code.js).

	17.4%	28.2%	js	       ReplaceCallback(JSContext*, unsigned long, void*)

0.4%	1943	    jschar *chars = rdata.cb.begin() + rdata.index;		
0.8%	1944	    rdata.index += growth;		
26.8%	1945	    js_strncpy(chars, left, leftlen);		
0.1%	1946	    chars += leftlen;		
	1947	    DoReplace(cx, rdata, chars);		

We can probably prefetch here.

	26.0%	26.0%	js	       js_ExecuteRegExp

	4233	        } else {		
4.2%	4234	            curState = &gData->stateStack[gData->stateStackTop];		
21.7%	4235	            switch (op) {		
	4236	              case REOP_END:		
	4237	                goto good;		

In both cases one PC location is responsible for almost all the L2 misses.