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From: "tromey at sourceware dot org" <sourceware-bugzilla@sourceware.org> To: gdb-prs@sourceware.org Subject: [Bug symtab/29105] New: new DWARF reader still slow Date: Fri, 29 Apr 2022 19:51:00 +0000 [thread overview] Message-ID: <bug-29105-4717@http.sourceware.org/bugzilla/> (raw) https://sourceware.org/bugzilla/show_bug.cgi?id=29105 Bug ID: 29105 Summary: new DWARF reader still slow Product: gdb Version: HEAD Status: NEW Severity: normal Priority: P2 Component: symtab Assignee: unassigned at sourceware dot org Reporter: tromey at sourceware dot org Target Milestone: --- Pedro pointed out that using the index cache is still faster than the new DWARF reader. I think I found why: What happens here is that gdb does the finalization step in the background. Interactively, this helps make it seem faster. However, it's not really faster, it is just deferring some work. You can see it with an invocation like: gdb -q -batch -iex 'set debug timestamp 1' -iex 'set debug dwarf-read 1' -ex start ./gdb Here for gdb-with-an-index I see: 0.820423 [dwarf-read] dwarf2_initialize_objfile: found gdb index from file 1.699175 [dwarf-read] process_queue: Expanding one or more symtabs of objfile /tmp/gdb.idx ... But for ordinary gdb: 1.310033 [dwarf-read] dwarf2_build_psymtabs_hard: Done building psymtabs of /tmp/gdb 4.666649 [dwarf-read] process_queue: Expanding one or more symtabs of objfile /tmp/gdb ... This is disappointing of course. It might be possible to reduce this time at the cost of a bit more complexity in the lookup code and perhaps a bit more memory use. For example, right now finalization merges the results from all the readers into a single entry table -- but maybe the table could remain sharded instead. Another possibility might be to do the work in worker threads and, instead of sharding the result, pre-sort the vectors and use a sorted merge operation to combine them. See the last messages in this thread: https://sourceware.org/pipermail/gdb-patches/2022-April/188194.html -- You are receiving this mail because: You are on the CC list for the bug.
next reply other threads:[~2022-04-29 19:51 UTC|newest] Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-04-29 19:51 tromey at sourceware dot org [this message] 2022-04-29 20:09 ` [Bug symtab/29105] " tromey at sourceware dot org 2022-05-13 20:56 ` tromey at sourceware dot org 2022-05-13 21:01 ` tromey at sourceware dot org 2022-05-16 18:51 ` tromey at sourceware dot org 2022-05-18 16:12 ` simon.marchi at polymtl dot ca 2022-05-20 1:54 ` simark at simark dot ca 2022-05-20 15:13 ` tromey at sourceware dot org 2022-05-20 15:36 ` simon.marchi at polymtl dot ca 2022-05-20 15:48 ` simon.marchi at polymtl dot ca 2022-05-26 13:49 ` cvs-commit at gcc dot gnu.org 2022-05-26 13:50 ` tromey at sourceware dot org 2022-07-13 16:49 ` tromey at sourceware dot org 2022-09-23 20:23 ` tromey at sourceware dot org 2022-09-23 20:44 ` tromey at sourceware dot org 2022-10-02 0:19 ` brobecker at gnat dot com 2022-10-06 20:44 ` tromey at sourceware dot org 2022-10-24 19:27 ` simon.marchi at polymtl dot ca 2022-11-01 20:42 ` tromey at sourceware dot org 2022-11-04 20:05 ` tromey at sourceware dot org 2022-11-04 20:10 ` simon.marchi at polymtl dot ca 2022-11-04 21:27 ` tromey at sourceware dot org 2022-11-04 21:28 ` tromey at sourceware dot org 2022-11-04 21:28 ` tromey at sourceware dot org 2022-11-05 1:28 ` simark at simark dot ca 2022-11-07 16:28 ` tromey at sourceware dot org 2022-11-16 0:09 ` tkacvins at gmail dot com 2022-11-16 0:56 ` simark at simark dot ca 2022-11-16 15:07 ` tkacvins at gmail dot com 2022-12-01 16:44 ` cvs-commit at gcc dot gnu.org 2022-12-01 18:18 ` cvs-commit at gcc dot gnu.org 2022-12-01 18:22 ` tromey at sourceware dot org 2022-12-14 10:23 ` cvs-commit at gcc dot gnu.org
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