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Re: profiling connection overhead

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: profiling connection overhead
Date: 2010-11-24 19:30:47
Message-ID: AANLkTi=8EWfpTpoo7ZHnw1_1-KwrfyWmM1DO6txq3yTp@mail.gmail.com (view raw, whole thread or download thread mbox)
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Lists: pgsql-hackers
On Wed, Nov 24, 2010 at 1:20 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> I tried configuring oprofile with --callgraph=10 and then running
> oprofile with -c, but it gives kooky looking output I can't interpret.

It looks like the trick is to compile with -fno-omit-frame-pointer.
New profiling run:

27563    10.3470  libc-2.11.2.so           memset
15162     5.6917  libc-2.11.2.so           memcpy
13471     5.0569  postgres                 hash_search_with_hash_value
13465     5.0547  postgres                 AllocSetAlloc
9513      3.5711  libc-2.11.2.so           _int_malloc
8729      3.2768  libc-2.11.2.so           fread
6336      2.3785  ld-2.11.2.so             do_lookup_x
5788      2.1728  ld-2.11.2.so             _dl_fixup
4995      1.8751  postgres                 MemoryContextAllocZero
4978      1.8687  ld-2.11.2.so             strcmp

Full results, and call graph, attached.  The first obvious fact is
that most of the memset overhead appears to be coming from
InitCatCache.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

Attachment: reconnect-callgraph.txt.bz2
Description: application/x-bzip2 (34.9 KB)
Attachment: reconnect-opreport.txt.bz2
Description: application/x-bzip2 (6.8 KB)

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