Hi,
I am trying to look at performance of V8. At this time, this is all on X86.
To build V8, I am using NDK compiler that comes when I download V8. That is
pretty straightforward process as mentioned. Once I build "release" or
"debug" V8, I ran mandreel and codeload Octance benchmarks with valgrind.
Then I use cg_annotate to look at Instruction count, data read/write,
branches etc. I am just curious where the bottlenecks are. I get the
following numbers for mandreel.
--------------------------------------------------------------------------------
Ir Dr Dw Bi Bc
--------------------------------------------------------------------------------
6,737,556,200 1,975,238,610 1,015,483,012 65,020,470 941,081,112 PROGRAM
TOTALS
--------------------------------------------------------------------------------
Ir Dr Dw Bi Bc file:function
--------------------------------------------------------------------------------
2,750,360,898 769,151,058 269,297,660 45,068,095 410,353,595 ???:???
165,387,529 59,780,937 25,440,838 9,340 27,302,136
???:v8::internal::Scanner::ScanIdentifierOrKeyword()
156,426,896 43,240,550 25,588,801 0 17,909,648
???:v8::internal::ExpressionClassifier<v8::internal::ParserTypes<v8::internal::Parser>
>::Accumulate(v8::internal::ExpressionClassifier<v8::internal::ParserTypes<v8::
internal::Parser> >*, unsigned int, bool)
150,476,281 44,181,365 28,594,154 3,145,871 9,250,952
???:v8::internal::Scanner::Scan()
..
..
It shows there there are 2.7billion instructions for ???:???. I am guessing
that these are the instructions that are reponsible for hidden classes,
loading/creating/deleting/accessing etc. If my guess is not correct, please
let me know. And then there are usual 165 million for
v8::internal::Scanner::ScanIdentifierOrKeyword(),150 million for scan() etc.
However, what is interesting is this - on the subsequent run on the same
machine, I see the following numbers:
--------------------------------------------------------------------------------
Ir Dr Dw Bi Bc
--------------------------------------------------------------------------------
12,369,840,202 3,844,013,654 1,701,470,472 248,336,756 1,605,561,615
PROGRAM TOTALS
--------------------------------------------------------------------------------
Ir Dr Dw Bi Bc
file:function
--------------------------------------------------------------------------------
6,361,147,238 2,029,054,548 684,679,708 228,306,958 762,170,252 ???:???
690,157,426 260,436,764 130,218,388 0 91,152,866
???:v8::internal::Runtime_TryInstallOptimizedCode(int,
v8::internal::Object**, v8::internal::Isolate*)
470,287,848 104,517,164 26,109,566 0 91,422,886
/build/glibc-bfm8X4/glibc-2.23/nptl/../nptl/pthread_mutex_lock.c:pthread_mutex_lock
365,612,760 104,464,484 13,067,997 0 104,438,144
/build/glibc-bfm8X4/glibc-2.23/nptl/pthread_mutex_unlock.c:pthread_mutex_unlock
364,611,492 91,152,878 104,174,716 0 13,021,838
???:v8::internal::StackGuard::CheckAndClearInterrupt(v8::internal::StackGuard::InterruptFlag)
165,387,529 59,780,937 25,440,838 9,340 27,302,136
???:v8::internal::Scanner::ScanIdentifierOrKeyword()
156,426,896 43,240,550 25,588,801 0 17,909,648
???:v8::internal::ExpressionClassifier<v8::internal::ParserTypes<v8::internal::Parser>
>::Accumulate(v8::internal::ExpressionClassifier<v8::internal::ParserTypes<v8::
internal::Parser> >*, unsigned int, bool)
150,476,281 44,181,365 28,594,154 3,145,871 9,250,952
???:v8::internal::Scanner::Scan()
All the numbers to the V8 functions remained the same; however all hidden
classes numbers and calls to the library went off the chart. For eg,
instructions dealing with hidden classes went from 2.7 billion to 6.3
billion. I don't see how using the same benchmark would make such huge
difference in the numbers. Can anyone please explain?
Also, how does V8 community look at performance numbers if not using
standard performance monitoring tools like valgrind? Is there any other way
to look at performance numbers?
Thanks.
Sirish
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