From: Luis Machado <luis.machado@arm.com>
To: Eli Zaretskii <eliz@gnu.org>, Tom Tromey <tom@tromey.com>
Cc: gdb-patches@sourceware.org
Subject: Re: Two observations using GDB 13 snapshot
Date: Wed, 28 Dec 2022 12:35:40 +0000 [thread overview]
Message-ID: <a56dcfa5-4950-a5a3-d12f-c99c57ca3b13@arm.com> (raw)
In-Reply-To: <835ydw20bw.fsf@gnu.org>
On 12/27/22 18:00, Eli Zaretskii wrote:
>> From: Tom Tromey <tom@tromey.com>
>> Cc: Tom Tromey <tom@tromey.com>, gdb-patches@sourceware.org,
>> luis.machado@arm.com
>> Date: Tue, 27 Dec 2022 10:19:24 -0700
>>
>> Eli> All I'm interested in is to help you and others understand what could
>> Eli> be the reason for slow reading of debug info at startup, so that it
>> Eli> could be sped up at some point.
>>
>> Ok. I re-read the thread and I see that at the beginning you didn't
>> mention -readnow. So, assuming that the -readnow stuff was a
>> distraction...
>
> Right. When it was brought up, I thought -readnow was indicative of
> what I see, but then you said it doesn't use the new DWARF reader
> code, so it is not relevant.
Sorry I brought -readnow up. I wasn't aware that mode didn't take advantage of the new DWARF reader. So it ended up
causing some confusion.
>
>> The new indexer should not be significantly slower even when
>> single-threaded. On my machine, if I "maint set worker-threads 0" and
>> then use a -O2 build of gdb, it's about as fast as the system /bin/gdb
>> (which uses the old code).
>>
>> Old:
>>
>> (gdb) file ./gdb
>> [...]
>> Command execution time: 2.408843 (cpu), 2.130013 (wall)
>>
>> New:
>>
>> (gdb) file ./gdb
>> [...]
>> Command execution time: 2.858222 (cpu), 2.865426 (wall)
>>
>> This is only slightly worse.
>
> My numbers are very different:
>
> . with GDB-12.1: elapsed: 8.39 sec, CPU: 6.25 sec
> . with gdb-13.0.50.20221217-git: elapsed: 135.8 sec, CPU: 130.5 sec
>
> No significant difference in memory consumption: 453MB for GDB 12.1,
> 441MB for GDB 13.
>
> (Interestingly, when reading symbols from Emacs on the same system,
> the times are almost identical: 2.593 for GDB 12 vs 2.671 for GDB 13.)
>
> Other details which might be important:
>
> GCC 9.2.0
> Binutils 2.39
> GDB compilation switches: -O2 -gdwarf-4 -g3
>
> And one more thing: this is a native 32-bit Windows build of GDB, so
> it has DWARF2 info in PE-COFF file, not in ELF. Maybe this could
> explain the difference? Or maybe the C++ code is a factor?
>
> Thanks.
next prev parent reply other threads:[~2022-12-28 12:36 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-17 17:42 Eli Zaretskii
2022-12-19 10:07 ` Luis Machado
2022-12-19 12:48 ` Eli Zaretskii
2022-12-19 14:08 ` Luis Machado
2022-12-19 14:45 ` Eli Zaretskii
2022-12-19 21:18 ` Tom Tromey
2022-12-20 3:26 ` Eli Zaretskii
2022-12-23 3:34 ` Simon Marchi
2022-12-23 8:05 ` Eli Zaretskii
2022-12-24 17:57 ` Tom Tromey
2022-12-24 18:13 ` Eli Zaretskii
2022-12-27 17:19 ` Tom Tromey
2022-12-27 18:00 ` Eli Zaretskii
2022-12-28 12:35 ` Luis Machado [this message]
2022-12-28 16:35 ` Tom Tromey
2022-12-28 17:35 ` Eli Zaretskii
2022-12-28 22:47 ` Tom Tromey
2022-12-29 15:18 ` Eli Zaretskii
2022-12-29 18:17 ` Tom Tromey
2022-12-29 18:36 ` John Baldwin
2022-12-29 19:13 ` Eli Zaretskii
2022-12-29 20:22 ` Simon Marchi
2022-12-30 14:31 ` Eli Zaretskii
2023-01-03 19:44 ` Christian Biesinger
2023-01-03 20:18 ` Eli Zaretskii
2023-01-03 20:34 ` Christian Biesinger
2023-01-03 21:34 ` Simon Marchi
2023-01-03 21:43 ` Christian Biesinger
2023-01-04 1:03 ` Tom Tromey
2023-01-04 18:10 ` Eli Zaretskii
2023-01-04 22:33 ` Tom Tromey
2023-01-05 7:11 ` Eli Zaretskii
2023-01-05 14:49 ` Christian Biesinger
2023-01-05 15:12 ` Eli Zaretskii
2023-01-06 20:55 ` Tom Tromey
2023-01-05 18:06 ` Torbjorn SVENSSON
2023-01-07 6:30 ` Eli Zaretskii
2023-01-07 9:14 ` Andreas Schwab
2023-01-07 9:32 ` Eli Zaretskii
2023-01-07 10:00 ` Andreas Schwab
2023-01-07 10:51 ` Eli Zaretskii
2023-01-07 13:04 ` Andreas Schwab
2023-01-07 13:54 ` Eli Zaretskii
2023-01-07 13:59 ` Andreas Schwab
2023-01-07 14:12 ` Eli Zaretskii
2023-01-07 14:23 ` Andreas Schwab
2023-01-07 14:29 ` Eli Zaretskii
2023-01-07 14:40 ` Andreas Schwab
2023-01-07 15:07 ` Eli Zaretskii
2023-01-07 15:40 ` Andreas Schwab
2023-01-07 16:10 ` Eli Zaretskii
2023-01-07 16:15 ` Eli Zaretskii
2023-01-07 16:16 ` Hannes Domani
2023-01-07 16:22 ` Eli Zaretskii
2023-01-07 17:39 ` Andreas Schwab
2023-01-07 18:08 ` Eli Zaretskii
2023-01-07 18:26 ` Andreas Schwab
2023-01-07 18:38 ` Eli Zaretskii
2023-01-07 19:26 ` Andreas Schwab
2023-01-07 19:35 ` Eli Zaretskii
2023-01-07 18:28 ` Hannes Domani
2023-01-07 19:25 ` Andreas Schwab
2023-01-07 15:07 ` Eli Zaretskii
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