Re: Parser Cruft in gram.y

On Wed, Dec 19, 2012 at 10:18 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)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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