192 lines
7.1 KiB
Diff
192 lines
7.1 KiB
Diff
http://sourceware.org/ml/gdb-patches/2014-10/msg00524.html
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Subject: [patch 1/2] Accelerate iter_match_first_hashed 1.8x
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--17pEHd4RhPHOinZp
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Content-Type: text/plain; charset=us-ascii
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Content-Disposition: inline
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Hi,
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very simple caching. dict_hash() is being called again and again for the same
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string.
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#0 in skip_spaces_const (chp=0x7fffb10f9bb6 "ts<char>, std::allocator<char> >::npos") at ./cli/cli-utils.c:244
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#1 in msymbol_hash_iw (string=0x7fffb10f9bb6 "ts<char>, std::allocator<char> >::npos") at minsyms.c:89
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#2 in dict_hash ( string0=0x7fffb10f9b90 "std::basic_string<char, std::char_traits<char>, std::allocator<char> >::npos") at dictionary.c:840
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#3 in iter_match_first_hashed (dict=0x105a7840, name=0x7fffb10f9b90 "std::basic_string<char, std::char_traits<char>, std::allocator<char> >::npos", compare=0x8b82f8 <strcmp_iw>, iterator=0x7fffb10f9970) at dictionary.c:659
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#4 in dict_iter_match_first (dict=0x105a7840, name=0x7fffb10f9b90 "std::basic_string<char, std::char_traits<char>, std::allocator<char> >::npos", compare=0x8b82f8 <strcmp_iw>, iterator=0x7fffb10f9970) at dictionary.c:555
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#5 in dict_iter_name_first (dict=0x105a7840, name=0x7fffb10f9b90 "std::basic_string<char, std::char_traits<char>, std::allocator<char> >::npos", iterator=0x7fffb10f9970) at dictionary.c:541
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#6 in block_iter_name_step (iterator=0x7fffb10f9960, name=0x7fffb10f9b90 "std::basic_string<char, std::char_traits<char>, std::allocator<char> >::npos", first=1) at block.c:580
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#7 in block_iter_name_first (block=0x10593e10, name=0x7fffb10f9b90 "std::basic_string<char, std::char_traits<char>, std::allocator<char> >::npos", iterator=0x7fffb10f9960) at block.c:609
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#8 in lookup_block_symbol (block=0x10593e10, name=0x7fffb10f9b90 "std::basic_string<char, std::char_traits<char>, std::allocator<char> >::npos", domain=VAR_DOMAIN) at symtab.c:2062
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#9 in lookup_symbol_aux_objfile (objfile=0x466f870, block_index=0, name=0x7fffb10f9b90 "std::basic_string<char, std::char_traits<char>, std::allocator<char> >::npos", domain=VAR_DOMAIN) at symtab.c:1664
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#10 in lookup_symbol_global_iterator_cb (objfile=0x466f870, cb_data=0x7fffb10f9ad0) at symtab.c:1868
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Maybe it could get cached at the caller but:
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* We would need to pass the hash value along the whole {dict,block}_iter_*
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call chain.
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* The DICT_VECTOR virtualization would get violated as dict_linear*_vector do
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not use any hash values.
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Jan
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--17pEHd4RhPHOinZp
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Content-Type: text/plain; charset=us-ascii
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Content-Disposition: inline; filename="idxcache1.patch"
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gdb/
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2014-10-20 Jan Kratochvil <jan.kratochvil@redhat.com>
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* dictionary.c (iter_match_first_hashed): Provide state cache for
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hash_index from NAME.
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diff --git a/gdb/dictionary.c b/gdb/dictionary.c
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index 055c87e..90bcd6d 100644
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--- a/gdb/dictionary.c
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+++ b/gdb/dictionary.c
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@@ -656,9 +656,26 @@ iter_match_first_hashed (const struct dictionary *dict, const char *name,
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symbol_compare_ftype *compare,
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struct dict_iterator *iterator)
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{
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- unsigned int hash_index = dict_hash (name) % DICT_HASHED_NBUCKETS (dict);
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+ unsigned int hash_index;
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struct symbol *sym;
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+ /* Cache HASH_INDEX. */
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+ {
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+ static const char *name_ptr_cached;
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+ static char *name_content_cached;
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+ static unsigned int dict_hash_cached;
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+
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+ if (name_ptr_cached != name || strcmp (name_content_cached, name) != 0)
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+ {
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+ dict_hash_cached = dict_hash (name);
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+ name_ptr_cached = name;
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+ xfree (name_content_cached);
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+ name_content_cached = xstrdup (name);
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+ }
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+ hash_index = dict_hash_cached;
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+ }
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+ hash_index %= DICT_HASHED_NBUCKETS (dict);
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+
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DICT_ITERATOR_DICT (iterator) = dict;
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/* Loop through the symbols in the given bucket, breaking when SYM
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--17pEHd4RhPHOinZp--
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http://sourceware.org/ml/gdb-patches/2014-10/msg00612.html
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Subject: [patchv2 2/2] Accelerate lookup_symbol_aux_objfile 14.5x [Re: [patch 0/2] Accelerate symbol lookups 15x]
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--vtzGhvizbBRQ85DL
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Content-Type: text/plain; charset=us-ascii
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Content-Disposition: inline
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On Wed, 22 Oct 2014 10:55:18 +0200, Doug Evans wrote:
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> For example, the count of calls to dict_hash before/after goes from 13.8M to 31.
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> I'm guessing one t hing we're doing here is coping with an artifact of
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> dwz:
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During my simple test on non-DWZ file (./gdb itself) it went 3684->3484.
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The problem is that dict_cash(val) is called for the same val for each block
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(== symtab).
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On DWZ the saving is probably much larger as there are many more symtabs due
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to DW_TAG_partial_unit ones.
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> what was once one global block to represent the entire objfile is
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> now N.
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Without DWZ there are X global blocks for X primary symtabs for X CUs of
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objfile. With DWZ there are X+Y global blocks for X+Y primary symtabs for
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X+Y CUs where Y are 'DW_TAG_partial_unit's.
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For 'DW_TAG_partial_unit's (Ys) their blockvector is usually empty. But not
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always, I have found there typedef symbols, there can IMO be optimized-out
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static variables etc.
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> [I'm sure the patches help in the non-dwz case, but I suspect it's less.
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> Which isn't to say the patches aren't useful.
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> I just need play with a few more examples.]
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I agree.
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[patch 2/2] could needlessly performance-regress non-DWZ cases, therefore
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I have put back original ALL_OBJFILE_PRIMARY_SYMTABS (instead of my
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ALL_OBJFILE_SYMTABS) as it is perfectly sufficient. For the performance
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testcase of mine:
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Benchmark on non-trivial application with 'p <tab><tab>':
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Command execution time: 4.215000 (cpu), 4.241466 (wall) --- both fixes with new [patch 2/2]
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Command execution time: 7.373000 (cpu), 7.395095 (wall) --- both fixes
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Command execution time: 13.572000 (cpu), 13.592689 (wall) --- just lookup_symbol_aux_objfile fix
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Command execution time: 113.036000 (cpu), 113.067995 (wall) --- FSF GDB HEAD
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That is additional 1.75x improvement, making the total improvement 26.8x.
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No regressions on {x86_64,x86_64-m32,i686}-fedora21pre-linux-gnu in standard
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and .gdb_index-enabled runs. Neither of the patches should cause any visible
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behavior change.
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Thanks,
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Jan
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--vtzGhvizbBRQ85DL
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Content-Type: text/plain; charset=us-ascii
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Content-Disposition: inline; filename="idxcache2doug.patch"
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gdb/
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2014-10-23 Jan Kratochvil <jan.kratochvil@redhat.com>
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* symtab.c (lookup_symbol_aux_objfile): Use ALL_OBJFILE_SYMTABS, inline
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lookup_block_symbol.
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diff --git a/gdb/symtab.c b/gdb/symtab.c
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index c530d50..da13861 100644
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--- a/gdb/symtab.c
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+++ b/gdb/symtab.c
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@@ -1657,15 +1657,25 @@ lookup_symbol_aux_objfile (struct objfile *objfile, int block_index,
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const struct block *block;
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struct symtab *s;
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+ gdb_assert (block_index == GLOBAL_BLOCK || block_index == STATIC_BLOCK);
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+
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ALL_OBJFILE_PRIMARY_SYMTABS (objfile, s)
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{
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+ struct dict_iterator dict_iter;
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+
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bv = BLOCKVECTOR (s);
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block = BLOCKVECTOR_BLOCK (bv, block_index);
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- sym = lookup_block_symbol (block, name, domain);
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- if (sym)
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+
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+ for (sym = dict_iter_name_first (block->dict, name, &dict_iter);
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+ sym != NULL;
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+ sym = dict_iter_name_next (name, &dict_iter))
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{
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- block_found = block;
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- return fixup_symbol_section (sym, objfile);
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+ if (symbol_matches_domain (SYMBOL_LANGUAGE (sym),
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+ SYMBOL_DOMAIN (sym), domain))
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+ {
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+ block_found = block;
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+ return fixup_symbol_section (sym, objfile);
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+ }
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}
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}
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--vtzGhvizbBRQ85DL--
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