From: Tom de Vries <tdevries@suse.de>
To: Tom Tromey <tom@tromey.com>, gdb-patches@sourceware.org
Subject: Re: [PATCH 00/14] Share DWARF partial symtabs between objfiles
Date: Sat, 22 Feb 2020 21:50:00 -0000 [thread overview]
Message-ID: <364adce2-d337-4851-84fb-adc125814228@suse.de> (raw)
In-Reply-To: <20200215165444.32653-1-tom@tromey.com>
On 15-02-2020 17:54, Tom Tromey wrote:
> A long-term goal for multi-inferior debugging has been to "split" an
> objfile, so that the bulk of the data can be shared across inferiors.
> Although a lot of progress has been made on this front, it has turned
> out to be surprisingly difficult to fully implement.
>
> "Recently" (a year or two ago) I realized that we could get most of
> the benefits of this split by sharing partial symbol tables. This is
> true because reading partial symbols is the slowest operation that
> users see -- in most cases, expanding a full symtab is reasonably
> quick.
>
> Implementing this also turned out to be tricky; but unlike the
> situation with types and symbols, it was possible to do incrementally.
>
> This series implements this idea for DWARF. It separates
> dwarf2_per_objfile into shareable and unshareable parts; then, when
> possible, the object is attached to the BFD.
>
> You can see the difference when timing "add-inferior -exec ./gdb",
> after "gdb ./gdb":
>
> Before: Command execution time: 1.667661 (cpu), 1.687607 (wall)
> After : Command execution time: 0.150011 (cpu), 0.151292 (wall)
>
> In this series I did not rename dwarf2_per_objfile. I'd prefer to do
> this after landing this series; it seemed like a large, mostly
> cosmetic, and yet hard-to-rebase patch. Also, I wanted to consult
> with everyone else about what we ought to call it.
>
> I also didn't attempt to implement this sharing for CTF. I don't
> really know much about CTF; but it seems like it ought to be possible.
> (Though I wonder if CTF wouldn't benefit more from simply bypassing
> partial symbols entirely.)
>
> Regression tested on x86-64 Fedora 28. I also did various tests by
> hand, and tested it by hand, under valgrind, on a gdb built with
> -fdebug-types-section.
>
> Like I mentioned earlier, this is a tricky series, so it would benefit
> from careful review. The main danger is that, if I missed a spot, we
> could end up in a situation where gdb will crash in a multi-inferior
> scenario.
I would like to take a look at this.
Is this tromey/t/reorganize-dwarf-code-sharing on your github?
Thanks,
- Tom
next prev parent reply other threads:[~2020-02-22 21:50 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-15 16:54 Tom Tromey
2020-02-15 16:55 ` [PATCH 02/14] Simplify setting of reading_partial_symbols Tom Tromey
2020-02-15 16:55 ` [PATCH 12/14] Fix a memory leak and remove an unused member Tom Tromey
2020-02-15 16:55 ` [PATCH 05/14] Introduce dwarf2_unshareable and move die_type_hash Tom Tromey
2020-02-18 11:23 ` Luis Machado
2020-02-19 4:20 ` Simon Marchi
2020-02-21 22:43 ` Tom Tromey
2020-02-15 16:55 ` [PATCH 14/14] Share DWARF partial symtabs Tom Tromey
2020-02-18 12:26 ` Luis Machado
2020-02-21 23:03 ` Tom Tromey
2020-02-15 16:55 ` [PATCH 03/14] Introduce dwarf2_per_objfile::obstack Tom Tromey
2020-02-19 4:13 ` Simon Marchi
2020-02-22 0:44 ` Tom Tromey
2020-02-15 16:55 ` [PATCH 11/14] Split type_unit_group Tom Tromey
2020-02-18 12:08 ` Luis Machado
2020-02-22 0:40 ` Tom Tromey
2020-02-15 16:55 ` [PATCH 10/14] Introduce dwarf2_enter_objfile and use it Tom Tromey
2020-02-18 11:58 ` Luis Machado
2020-02-21 22:54 ` Tom Tromey
2020-02-15 16:55 ` [PATCH 07/14] Add dwarf2_per_cu_data::index Tom Tromey
2020-02-18 11:39 ` Luis Machado
2020-02-21 23:36 ` Tom Tromey
2020-02-19 4:36 ` Simon Marchi
2020-02-19 5:31 ` Simon Marchi
2020-02-21 23:41 ` Tom Tromey
2020-02-21 23:41 ` Tom Tromey
2020-02-15 16:55 ` [PATCH 06/14] Add "objfile" parameter to two partial_symtab methods Tom Tromey
2020-02-18 11:26 ` Luis Machado
2020-02-15 16:55 ` [PATCH 04/14] Convert IS_TYPE_UNIT_GROUP to method Tom Tromey
2020-02-15 16:55 ` [PATCH 08/14] Remove symtab links from dwarf2_psymtab and dwarf2_per_cu_quick_data Tom Tromey
2020-02-18 11:50 ` Luis Machado
2020-02-19 4:47 ` Simon Marchi
2020-02-22 0:38 ` Tom Tromey
2020-02-22 0:36 ` Tom Tromey
2020-02-15 16:55 ` [PATCH 09/14] Add objfile member to DWARF batons Tom Tromey
2020-02-15 16:55 ` [PATCH 13/14] Move signatured_type::type to unshareable object Tom Tromey
2020-02-15 16:55 ` [PATCH 01/14] Fix latent bug in dwarf2_find_containing_comp_unit Tom Tromey
2020-02-19 3:42 ` Simon Marchi
2020-02-19 14:08 ` Tom Tromey
2020-02-20 0:11 ` Tom Tromey
2020-02-20 0:12 ` Tom Tromey
[not found] ` <3a3f1f39-c715-58ba-06a8-2980afb82c53@simark.ca>
2020-02-20 16:50 ` Tom Tromey
2020-03-07 19:12 ` Christian Biesinger
2020-02-17 12:31 ` [PATCH 00/14] Share DWARF partial symtabs between objfiles Luis Machado
2020-02-17 16:59 ` Tom Tromey
2020-02-22 21:50 ` Tom de Vries [this message]
2020-02-22 22:01 ` Tom Tromey
2020-02-23 2:37 ` Simon Marchi
2020-02-23 23:58 ` Tom Tromey
2020-02-24 2:52 ` Simon Marchi
2020-02-24 3:07 ` Tom Tromey
2020-02-24 3:22 ` Tom Tromey
2020-02-24 13:42 ` Tom de Vries
2020-02-24 16:00 ` Tom de Vries
2020-02-24 17:29 ` Tom Tromey
2020-02-24 23:15 ` Tom Tromey
2020-02-24 19:18 ` Simon Marchi
2020-02-24 23:20 ` Tom Tromey
2020-02-24 22:48 ` Tom Tromey
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