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From: "vries at gcc dot gnu.org" <sourceware-bugzilla@sourceware.org>
To: gdb-prs@sourceware.org
Subject: [Bug gdb/25703] New: set dwarf max-cache-age default of 5 is slow
 for inter-CU-reference binaries
Date: Fri, 20 Mar 2020 09:05:31 +0000
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https://sourceware.org/bugzilla/show_bug.cgi?id=3D25703

            Bug ID: 25703
           Summary: set dwarf max-cache-age default of 5 is slow for
                    inter-CU-reference binaries
           Product: gdb
           Version: HEAD
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: gdb
          Assignee: unassigned at sourceware dot org
          Reporter: vries at gcc dot gnu.org
  Target Milestone: ---

In gdb/dwarf2/read.c, we find the default setting for "set dwarf
max-cache-age":
...
/* Loaded secondary compilation units are kept in memory until they=20=20=
=20=20=20=20=20=20=20=20=20=20=20
   have not been referenced for the processing of this many=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20
   compilation units.  Set this to zero to disable caching.  Cache=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20
   sizes of up to at least twenty will improve startup time for=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20
   typical inter-CU-reference binaries, at an obvious memory cost.  */
static int dwarf_max_cache_age =3D 5;
...

See PR23710 comment 5 for an example where indeed increasing this setting f=
or
an inter-cu-reference binary reducing loading time with 16.5%.

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