subject:"PR 54075 Restore 4.6 growth factor"

Re: PR 54075 Restore 4.6 growth factor

2012-07-29 Thread Paolo Carlini


On 07/29/2012 07:38 PM, Jonathan Wakely wrote:
Yes please. The point is to allow people to review and comment before 
the patch is applied, and some people only subscribe to gcc-patches 
not libstdc++.
I don't have a strong opinion, but I must say that I don't understand 
why those people don't subscribe to libstdc++: since we *do* have a 
separate mailing list, IMO if they are interested they should. On the 
other hand, if they *really* don't care (eg, some people don't even like 
C++ in general ;) sending all the traffic to gcc-patches too may seem a 
mild form of spamming. But, as I said, I don't have a strong opinion, 
and personally I'm not terribly consistent ;)


Paolo.

Re: PR 54075 Restore 4.6 growth factor

2012-07-29 Thread Jonathan Wakely

On 29 July 2012 18:15, François Dumont wrote:
> Patch applied. I usually CC to gcc-patches when I signal that it has been
> applied. Should I send it all my patch proposals ?

Yes please. The point is to allow people to review and comment before
the patch is applied, and some people only subscribe to gcc-patches
not libstdc++.  The gcc-cvs and libstdc++-cvs lists provide a record
of patches that have been applied.

Re: PR 54075 Restore 4.6 growth factor

2012-07-29 Thread François Dumont

Patch applied. I usually CC to gcc-patches when I signal that it has 
been applied. Should I send it all my patch proposals ?


François

On 07/28/2012 11:18 PM, Jonathan Wakely wrote:

Please remember to CC gcc-patches too.

On 28 July 2012 21:49, François Dumont wrote:

Hi

 Here is the patch to restore the 4.6 growth factor of 2. I prefer to
validate the restored behavior by adding a performance test. Without the
patch the result was:

unordered_set.cc unordered_set 1000 insertions  403r  329u
73s 402825280mem0pf

after the patch:

unordered_set.cc unordered_set 1000 insertions  112r   86u
25s 402825104mem0pf

It validates the 3x times performance hint.

Tested under Linux x86_64.

2012-07-28  François Dumont  

 PR libstdc++/54075
 * include/bits/hashtable_policy.h
 (_Prime_rehash_policy::_M_next_bkt): Add a growth factor set to 2
 to boost growth in the number of buckets.
 * testsuite/performance/23_containers/insert/unordered_set.cc: New.

Even if it is not a Standard conformity issue I think we can apply it to the
4.7 branch too.

Yes, it's a performance regression, so this is OK for trunk and 4.7, thanks.


Index: include/bits/hashtable_policy.h
===
--- include/bits/hashtable_policy.h	(revision 189893)
+++ include/bits/hashtable_policy.h	(working copy)
@@ -395,6 +395,8 @@
 
 enum { _S_n_primes = sizeof(unsigned long) != 8 ? 256 : 256 + 48 };
 
+static const std::size_t _S_growth_factor = 2;
+
 float_M_max_load_factor;
 mutable std::size_t  _M_prev_resize;
 mutable std::size_t  _M_next_resize;
@@ -415,28 +417,27 @@
 static const unsigned char __fast_bkt[12]
   = { 2, 2, 2, 3, 5, 5, 7, 7, 11, 11, 11, 11 };
 
-if (__n <= 11)
+const std::size_t __grown_n = __n * _S_growth_factor;
+if (__grown_n <= 11)
   {
 	_M_prev_resize = 0;
 	_M_next_resize
-	  = __builtin_ceil(__fast_bkt[__n] * (long double)_M_max_load_factor);
-	return __fast_bkt[__n];
+	  = __builtin_ceil(__fast_bkt[__grown_n]
+			   * (long double)_M_max_load_factor);
+	return __fast_bkt[__grown_n];
   }
 
-const unsigned long* __p
-  = std::lower_bound(__prime_list + 5, __prime_list + _S_n_primes, __n);
+const unsigned long* __next_bkt
+  = std::lower_bound(__prime_list + 5, __prime_list + _S_n_primes,
+			 __grown_n);
+const unsigned long* __prev_bkt
+  = std::lower_bound(__prime_list + 1, __next_bkt, __n / _S_growth_factor);
 
-// Shrink will take place only if the number of elements is small enough
-// so that the prime number 2 steps before __p is large enough to still
-// conform to the max load factor:
 _M_prev_resize
-  = __builtin_floor(*(__p - 2) * (long double)_M_max_load_factor);
-
-// Let's guaranty that a minimal grow step of 11 is used
-if (*__p - __n < 11)
-  __p = std::lower_bound(__p, __prime_list + _S_n_primes, __n + 11);
-_M_next_resize = __builtin_ceil(*__p * (long double)_M_max_load_factor);
-return *__p;
+  = __builtin_floor(*(__prev_bkt - 1) * (long double)_M_max_load_factor);
+_M_next_resize
+  = __builtin_ceil(*__next_bkt * (long double)_M_max_load_factor);
+return *__next_bkt;
   }
 
   // Return the smallest prime p such that alpha p >= n, where alpha
Index: testsuite/performance/23_containers/insert/unordered_set.cc
===
--- testsuite/performance/23_containers/insert/unordered_set.cc	(revision 0)
+++ testsuite/performance/23_containers/insert/unordered_set.cc	(revision 0)
@@ -0,0 +1,42 @@
+// Copyright (C) 2012 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// .
+
+// { dg-options "-std=c++11" }
+
+#include 
+#include 
+
+int main()
+{
+  using namespace __gnu_test;
+
+  time_counter time;
+  resource_counter resource;
+
+  const int sz = 1000;
+
+  std::unordered_set s;
+  start_counters(time, resource);
+
+  for (int i = 0; i != sz ; ++i)
+s.insert(i);
+
+  stop_counters(time, resource);
+  report_performance(__FILE__, "unordered_set 1000 insertions",
+		 time, resource);
+  return 0;
+}

Re: PR 54075 Restore 4.6 growth factor

2012-07-28 Thread Jonathan Wakely

Please remember to CC gcc-patches too.

On 28 July 2012 21:49, François Dumont wrote:
> Hi
>
> Here is the patch to restore the 4.6 growth factor of 2. I prefer to
> validate the restored behavior by adding a performance test. Without the
> patch the result was:
>
> unordered_set.cc unordered_set 1000 insertions  403r  329u
> 73s 402825280mem0pf
>
> after the patch:
>
> unordered_set.cc unordered_set 1000 insertions  112r   86u
> 25s 402825104mem0pf
>
> It validates the 3x times performance hint.
>
> Tested under Linux x86_64.
>
> 2012-07-28  François Dumont  
>
> PR libstdc++/54075
> * include/bits/hashtable_policy.h
> (_Prime_rehash_policy::_M_next_bkt): Add a growth factor set to 2
> to boost growth in the number of buckets.
> * testsuite/performance/23_containers/insert/unordered_set.cc: New.
>
> Even if it is not a Standard conformity issue I think we can apply it to the
> 4.7 branch too.

Yes, it's a performance regression, so this is OK for trunk and 4.7, thanks.
Index: include/bits/hashtable_policy.h
===
--- include/bits/hashtable_policy.h	(revision 189893)
+++ include/bits/hashtable_policy.h	(working copy)
@@ -395,6 +395,8 @@
 
 enum { _S_n_primes = sizeof(unsigned long) != 8 ? 256 : 256 + 48 };
 
+static const std::size_t _S_growth_factor = 2;
+
 float_M_max_load_factor;
 mutable std::size_t  _M_prev_resize;
 mutable std::size_t  _M_next_resize;
@@ -415,28 +417,27 @@
 static const unsigned char __fast_bkt[12]
   = { 2, 2, 2, 3, 5, 5, 7, 7, 11, 11, 11, 11 };
 
-if (__n <= 11)
+const std::size_t __grown_n = __n * _S_growth_factor;
+if (__grown_n <= 11)
   {
 	_M_prev_resize = 0;
 	_M_next_resize
-	  = __builtin_ceil(__fast_bkt[__n] * (long double)_M_max_load_factor);
-	return __fast_bkt[__n];
+	  = __builtin_ceil(__fast_bkt[__grown_n]
+			   * (long double)_M_max_load_factor);
+	return __fast_bkt[__grown_n];
   }
 
-const unsigned long* __p
-  = std::lower_bound(__prime_list + 5, __prime_list + _S_n_primes, __n);
+const unsigned long* __next_bkt
+  = std::lower_bound(__prime_list + 5, __prime_list + _S_n_primes,
+			 __grown_n);
+const unsigned long* __prev_bkt
+  = std::lower_bound(__prime_list + 1, __next_bkt, __n / _S_growth_factor);
 
-// Shrink will take place only if the number of elements is small enough
-// so that the prime number 2 steps before __p is large enough to still
-// conform to the max load factor:
 _M_prev_resize
-  = __builtin_floor(*(__p - 2) * (long double)_M_max_load_factor);
-
-// Let's guaranty that a minimal grow step of 11 is used
-if (*__p - __n < 11)
-  __p = std::lower_bound(__p, __prime_list + _S_n_primes, __n + 11);
-_M_next_resize = __builtin_ceil(*__p * (long double)_M_max_load_factor);
-return *__p;
+  = __builtin_floor(*(__prev_bkt - 1) * (long double)_M_max_load_factor);
+_M_next_resize
+  = __builtin_ceil(*__next_bkt * (long double)_M_max_load_factor);
+return *__next_bkt;
   }
 
   // Return the smallest prime p such that alpha p >= n, where alpha
Index: testsuite/performance/23_containers/insert/unordered_set.cc
===
--- testsuite/performance/23_containers/insert/unordered_set.cc	(revision 0)
+++ testsuite/performance/23_containers/insert/unordered_set.cc	(revision 0)
@@ -0,0 +1,42 @@
+// Copyright (C) 2012 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// .
+
+// { dg-options "-std=c++11" }
+
+#include 
+#include 
+
+int main()
+{
+  using namespace __gnu_test;
+
+  time_counter time;
+  resource_counter resource;
+
+  const int sz = 1000;
+
+  std::unordered_set s;
+  start_counters(time, resource);
+
+  for (int i = 0; i != sz ; ++i)
+s.insert(i);
+
+  stop_counters(time, resource);
+  report_performance(__FILE__, "unordered_set 1000 insertions",
+		 time, resource);
+  return 0;
+}

Re: PR 54075 Restore 4.6 growth factor

Re: PR 54075 Restore 4.6 growth factor

Re: PR 54075 Restore 4.6 growth factor

Re: PR 54075 Restore 4.6 growth factor

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