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Backport vDSO regression. 

- Revert the makeinfo workaround from 7.8-27.fc21.
- Further 1.75x improvement of the interactive symbols lookup (Doug Evans).
This commit is contained in:
Jan Kratochvil 2014-10-27 15:47:21 +01:00
parent 862e0ed47f
commit 8095c33951
3 changed files with 163 additions and 25 deletions
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76
gdb-symbols-lookup-accel.patch
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@ -78,49 +78,91 @@ index 055c87e..90bcd6d 100644
--17pEHd4RhPHOinZp-- --17pEHd4RhPHOinZp--
http://sourceware.org/ml/gdb-patches/2014-10/msg00525.html
Subject: [patch 2/2] Accelerate lookup_symbol_aux_objfile 8x
--K8nIJk4ghYZn606h http://sourceware.org/ml/gdb-patches/2014-10/msg00612.html
Subject: [patchv2 2/2] Accelerate lookup_symbol_aux_objfile 14.5x [Re: [patch 0/2] Accelerate symbol lookups 15x]
--vtzGhvizbBRQ85DL
Content-Type: text/plain; charset=us-ascii Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline Content-Disposition: inline
Hi, On Wed, 22 Oct 2014 10:55:18 +0200, Doug Evans wrote:
> For example, the count of calls to dict_hash before/after goes from 13.8M to 31.
> I'm guessing one t hing we're doing here is coping with an artifact of
> dwz:
lookup_symbol_aux_objfile() processing is very ineffective. For each primary During my simple test on non-DWZ file (./gdb itself) it went 3684->3484.
symtab it searches it and also all its secondary symtabs. But that means that
secondary symtabs included in many primary symtabs get needlessly searched
many times during one lookup_symbol_aux_objfile() run.
lookup_symbol_aux_objfile does not care in which primary/secondary symtab the The problem is that dict_cash(val) is called for the same val for each block
symbol is found. (== symtab).
On DWZ the saving is probably much larger as there are many more symtabs due
to DW_TAG_partial_unit ones.
> what was once one global block to represent the entire objfile is
> now N.
Without DWZ there are X global blocks for X primary symtabs for X CUs of
objfile. With DWZ there are X+Y global blocks for X+Y primary symtabs for
X+Y CUs where Y are 'DW_TAG_partial_unit's.
For 'DW_TAG_partial_unit's (Ys) their blockvector is usually empty. But not
always, I have found there typedef symbols, there can IMO be optimized-out
static variables etc.
> [I'm sure the patches help in the non-dwz case, but I suspect it's less.
> Which isn't to say the patches aren't useful.
> I just need play with a few more examples.]
I agree.
[patch 2/2] could needlessly performance-regress non-DWZ cases, therefore
I have put back original ALL_OBJFILE_PRIMARY_SYMTABS (instead of my
ALL_OBJFILE_SYMTABS) as it is perfectly sufficient. For the performance
testcase of mine:
Benchmark on non-trivial application with 'p <tab><tab>':
Command execution time: 4.215000 (cpu), 4.241466 (wall) --- both fixes with new [patch 2/2]
Command execution time: 7.373000 (cpu), 7.395095 (wall) --- both fixes
Command execution time: 13.572000 (cpu), 13.592689 (wall) --- just lookup_symbol_aux_objfile fix
Command execution time: 113.036000 (cpu), 113.067995 (wall) --- FSF GDB HEAD
That is additional 1.75x improvement, making the total improvement 26.8x.
No regressions on {x86_64,x86_64-m32,i686}-fedora21pre-linux-gnu in standard
and .gdb_index-enabled runs. Neither of the patches should cause any visible
behavior change.
Thanks,
Jan Jan
--K8nIJk4ghYZn606h --vtzGhvizbBRQ85DL
Content-Type: text/plain; charset=us-ascii Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline; filename="idxcache2.patch" Content-Disposition: inline; filename="idxcache2doug.patch"
gdb/ gdb/
2014-10-20 Jan Kratochvil <jan.kratochvil@redhat.com> 2014-10-23 Jan Kratochvil <jan.kratochvil@redhat.com>
* symtab.c (lookup_symbol_aux_objfile): Use ALL_OBJFILE_SYMTABS, inline * symtab.c (lookup_symbol_aux_objfile): Use ALL_OBJFILE_SYMTABS, inline
lookup_block_symbol. lookup_block_symbol.
diff --git a/gdb/symtab.c b/gdb/symtab.c diff --git a/gdb/symtab.c b/gdb/symtab.c
index c530d50..bc800ef 100644 index c530d50..da13861 100644
--- a/gdb/symtab.c --- a/gdb/symtab.c
+++ b/gdb/symtab.c +++ b/gdb/symtab.c
@@ -1657,15 +1657,25 @@ lookup_symbol_aux_objfile (struct objfile *objfile, int block_index, @@ -1657,15 +1657,25 @@ lookup_symbol_aux_objfile (struct objfile *objfile, int block_index,
const struct block *block; const struct block *block;
struct symtab *s; struct symtab *s;
- ALL_OBJFILE_PRIMARY_SYMTABS (objfile, s)
+ gdb_assert (block_index == GLOBAL_BLOCK || block_index == STATIC_BLOCK); + gdb_assert (block_index == GLOBAL_BLOCK || block_index == STATIC_BLOCK);
+ +
+ ALL_OBJFILE_SYMTABS (objfile, s) ALL_OBJFILE_PRIMARY_SYMTABS (objfile, s)
{ {
+ struct dict_iterator dict_iter; + struct dict_iterator dict_iter;
+ +
@ -145,5 +187,5 @@ index c530d50..bc800ef 100644
} }
--K8nIJk4ghYZn606h-- --vtzGhvizbBRQ85DL--

98
gdb-upstream.patch
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@ -1770,3 +1770,101 @@ gdb/testsuite/
-- --
1.9.3 1.9.3
commit 54fbc750b54271efb75ae11ce49f14c4234a9476
Author: Jan Kratochvil <jan.kratochvil@redhat.com>
Date: Thu Sep 18 08:21:40 2014 +0200
Fix regression for Linux vDSO in GDB (PR gdb/17407).
since
5979d6b69b20a8355ea94b75fad97415fce4788c
https://sourceware.org/git/?p=binutils-gdb.git;a=commitdiff;h=5979d6b69b20a8355ea94b75fad97415fce4788c
vdso handling
https://sourceware.org/ml/binutils/2014-03/msg00082.html
https://sourceware.org/ml/binutils/2014-04/msg00003.html
Message-ID: <A78C989F6D9628469189715575E55B230AA884EB@IRSMSX104.ger.corp.intel.com>
I get on
kernel-3.16.2-200.fc20.x86_64
https://koji.fedoraproject.org/koji/buildinfo?buildID=575860
attaching its vdso.bin.gz
GDB (FSF HEAD 5e43d46791c4c66fd83947a12d4f716b561a9103) regression:
reproducer:
./gdb -ex start ./gdb
actual result / FAIL:
Got object file from memory but can't read symbols: File truncated.
expected result / PASS:
<nothing>
or / PASS:
warning: Could not load shared library symbols for linux-vdso.so.1.
Do you need "set solib-search-path" or "set sysroot"?
That "warning: Could not load shared library..." is mostly harmless (it is
a bug in GDB), in the FAIL case it is not printed just because
bfd_check_format() fails there.
It seems logical to me this way when the 'size' parameter has been already
added.
Alan Modra:
I was wrongly thinking that the section headers were
always last when I wrote that code. (They are now! If you relink
that vdso with current binutils master you won't hit this problem, but
that of course doesn't help existing kernels.)
I do not see a regression for add-symbol-file-from-memory for libncurses.so.5
from the original thread above.
Start of section headers: 1080 (bytes into file)
Size of section headers: 64 (bytes)
Number of section headers: 13
Section header string table index: 8
Section Headers:
[Nr] Name Type Address Off Size ES Flg Lk Inf Al
[ 8] .fake_shstrtab STRTAB 0000000000000780 000780 000076 00 A 0 0 32
Program Headers:
Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
LOAD 0x000000 0x0000000000000000 0x0000000000000000 0x0012fe 0x0012fe R E 0x1000
size == 0x2000
shdr_end == 0x778 == 1080 + 13 * 64
high_offset == 0x12fe
else if (size >= shdr_end)
- high_offset = shdr_end;
+ high_offset = size;
But then 0x778 < 0x780 for "Section header string table index" so whole
bfd_check_format() fails because section headers were not cleared here:
/* If the segments visible in memory didn't include the section headers,
then clear them from the file header. */
if (high_offset < shdr_end)
bfd/ChangeLog
2014-09-18 Jan Kratochvil <jan.kratochvil@redhat.com>
PR gdb/17407
* elfcode.h (bfd_from_remote_memory): Use SIZE for HIGH_OFFSET.
### a/bfd/ChangeLog
### b/bfd/ChangeLog
## -1,3 +1,8 @@
+2014-09-18 Jan Kratochvil <jan.kratochvil@redhat.com>
+
+ PR gdb/17407
+ * elfcode.h (bfd_from_remote_memory): Use SIZE for HIGH_OFFSET.
+
2014-07-16 H.J. Lu <hongjiu.lu@intel.com>
* elf32-i386.c (elf_i386_plt_sym_val): Match PLT entry only for
--- a/bfd/elfcode.h
+++ b/bfd/elfcode.h
@@ -1749,7 +1749,7 @@ NAME(_bfd_elf,bfd_from_remote_memory)
headers. */
}
else if (size >= shdr_end)
- high_offset = shdr_end;
+ high_offset = size;
else
{
bfd_vma page_size = get_elf_backend_data (templ)->minpagesize;

14
gdb.spec
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@ -26,7 +26,7 @@ Version: 7.8
# The release always contains a leading reserved number, start it at 1. # The release always contains a leading reserved number, start it at 1.
# `upstream' is not a part of `name' to stay fully rpm dependencies compatible for the testing. # `upstream' is not a part of `name' to stay fully rpm dependencies compatible for the testing.
Release: 28%{?dist} Release: 29%{?dist}
License: GPLv3+ and GPLv3+ with exceptions and GPLv2+ and GPLv2+ with exceptions and GPL+ and LGPLv2+ and BSD and Public Domain and GFDL License: GPLv3+ and GPLv3+ with exceptions and GPLv2+ and GPLv2+ with exceptions and GPL+ and LGPLv2+ and BSD and Public Domain and GFDL
Group: Development/Debuggers Group: Development/Debuggers
@ -897,9 +897,6 @@ mv -f readline-doc readline/doc
%build %build
rm -rf %{buildroot} rm -rf %{buildroot}
# https://bugzilla.redhat.com/show_bug.cgi?id=1154436
export PERL5LIB="$PERL5LIB${PERL5LIB:+:}/usr/share/texi2html/lib/Unicode-EastAsianWidth/lib"
# Identify the build directory with the version of gdb as well as the # Identify the build directory with the version of gdb as well as the
# architecture, to allow for mutliple versions to be installed and # architecture, to allow for mutliple versions to be installed and
# built. # built.
@ -1130,10 +1127,6 @@ echo ====================TESTING END=====================
%endif %endif
%install %install
# https://bugzilla.redhat.com/show_bug.cgi?id=1154436
export PERL5LIB="$PERL5LIB${PERL5LIB:+:}/usr/share/texi2html/lib/Unicode-EastAsianWidth/lib"
# Initially we're in the %{gdb_src} directory. # Initially we're in the %{gdb_src} directory.
cd %{gdb_build} cd %{gdb_build}
rm -rf $RPM_BUILD_ROOT rm -rf $RPM_BUILD_ROOT
@ -1350,6 +1343,11 @@ then
fi fi
%changelog %changelog
* Mon Oct 27 2014 Jan Kratochvil <jan.kratochvil@redhat.com> - 7.8-29.fc21
- Backport vDSO regression.
- Revert the makeinfo workaround from 7.8-27.fc21.
- Further 1.75x improvement of the interactive symbols lookup (Doug Evans).
* Mon Oct 20 2014 Jan Kratochvil <jan.kratochvil@redhat.com> - 7.8-28.fc21 * Mon Oct 20 2014 Jan Kratochvil <jan.kratochvil@redhat.com> - 7.8-28.fc21
- Accelerate interactive symbols lookup 15x. - Accelerate interactive symbols lookup 15x.