Re: Parser Cruft in gram.y

On Wed, Dec 19, 2012 at 10:18 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> valgrind comes with a tool called cachegrind which can emulate the
>> cache algorithm on some variants of various cpus and produce reports.
>> Can it be made to produce a report for a specific block of memory?
>
> I believe that oprofile can be persuaded to produce statistics about
> where in one's code are the most cache misses, not just the most
> wall-clock ticks; which would shed a lot of light on this question.
> However, my oprofile-fu doesn't quite extend to actually persuading it.

perf can certainly do this.

$ perf record -a -e cache-misses pgbench -n -S -T 30
...output elided...
$ perf report -d postgres | grep -v '^#' | head    8.88%   postgres  base_yyparse    7.05%    swapper  0x807c    4.67%
postgres  SearchCatCache    3.77%    pgbench  0x172dd58    3.47%   postgres  hash_search_with_hash_value    3.23%
postgres AllocSetAlloc    2.58%   postgres  core_yylex    1.87%   postgres  LWLockAcquire    1.83%   postgres
fmgr_info_cxt_security   1.75%   postgres  0x4d1054
 

For comparison:

$ perf record -a -e cycles -d postgres pgbench -n -S -T 30
$ perf report -d postgres | grep -v '^#' | head    6.54%     postgres  AllocSetAlloc    4.08%      swapper  0x4ce754
3.60%    postgres  hash_search_with_hash_value    2.74%     postgres  base_yyparse    2.71%     postgres
MemoryContextAllocZeroAligned   2.57%     postgres  MemoryContextAlloc    2.36%     postgres  SearchCatCache    2.10%
 postgres  _bt_compare    1.70%     postgres  LWLockAcquire    1.54%     postgres  FunctionCall2Coll
 

-- 
Robert Haas
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