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Re: [RFC] symbol lookup cache
- From: Doug Evans <dje at google dot com>
- To: gdb-patches <gdb-patches at sourceware dot org>, Joel Brobecker <brobecker at adacore dot com>
- Date: Tue, 2 Dec 2014 16:50:11 -0800
- Subject: Re: [RFC] symbol lookup cache
- Authentication-results: sourceware.org; auth=none
- References: <yjt2y4qrlqwa dot fsf at ruffy dot mtv dot corp dot google dot com>
On Mon, Dec 1, 2014 at 12:23 AM, Doug Evans <dje@google.com> wrote:
>
> Hi.
>
> Holidays are nice for having the time to take on
> projects one is interested in but doesn't have
> time to otherwise do.
>
> I looked at a couple of areas for improvement
> in gdb's symbol handling over the last couple
> of days. One is .gdb_index support for tab
> completion, which is the topic for another mail.
> This email is about a symbol lookup cache.
>
> ..gdb_index helps speed things up for one objfile,
> but when there are 100s (or 1000s) of shared
> libraries, symbol lookup can still take awhile,
> even with .gdb_index.
> [I'm setting aside a planned change to basic
> symbol lookup to use the index better.
> We'll still, I think, want a cache even
> with that change.]
>
> This patch still needs more testing
> and I need to collect more perf data,
> but it's a start at caching symbol lookups.
> This first pass is just for the case
> where we iterate over all objfiles for
> lookups in the global or static blocks.
> Low hanging fruit.
> At the moment it's just RFC.
[bleah, sorry for the repeat Joel]
One thing this patch is missing is the ability to turn the cache off,
both for performance measurements and for debugging.