maria-developers team mailing list archive

[Sergey Vojtovich <svoj@xxxxxxxxxxx>]

Hi!

JFYI: we discussed this during the Barcelona meeting. I will submit table cache
part separately (not to overcomplicate this patch). Reviewers are very welcome.

Regards,
Sergey


----- Forwarded message from Sergey Vojtovich <svoj@xxxxxxxxxxx> -----

Date: Fri, 14 Feb 2014 12:25:50 +0000 (UTC)
From: Sergey Vojtovich <svoj@xxxxxxxxxxx>
To: commits@xxxxxxxxxxx
Subject: [Commits] Rev 4006: MDEV-5674 - Performance: my_hash_sort_bin is called too often in lp:maria/10.0

At lp:maria/10.0

------------------------------------------------------------
revno: 4006
revision-id: svoj@xxxxxxxxxxx-20140214122541-tenvcllk760deai8
parent: svoj@xxxxxxxxxxx-20140213071355-psk0jpsarx2u7myc
committer: Sergey Vojtovich <svoj@xxxxxxxxxxx>
branch nick: 10.0
timestamp: Fri 2014-02-14 16:25:41 +0400
message:
  MDEV-5674 - Performance: my_hash_sort_bin is called too often
  
  - reduced number of my_hash_sort_bin() calls from 4 to 2 per query.
    Let MDL subsystem use pre-calculated hash value for hash
    inserts and deletes.
  - reduced number of memory accesses done by my_hash_sort_bin()
=== modified file 'include/hash.h'
--- a/include/hash.h	2013-09-14 01:09:36 +0000
+++ b/include/hash.h	2014-02-14 12:25:41 +0000
@@ -86,7 +86,13 @@ uchar *my_hash_first_from_hash_value(con
 uchar *my_hash_next(const HASH *info, const uchar *key, size_t length,
                     HASH_SEARCH_STATE *state);
 my_bool my_hash_insert(HASH *info, const uchar *data);
+my_bool my_hash_insert_using_hash_value(HASH *info,
+                                        my_hash_value_type hash_value,
+                                        const uchar *record);
 my_bool my_hash_delete(HASH *hash, uchar *record);
+my_bool my_hash_delete_using_hash_value(HASH *hash,
+                                        my_hash_value_type hash_value,
+                                        uchar *record);
 my_bool my_hash_update(HASH *hash, uchar *record, uchar *old_key,
                        size_t old_key_length);
 void my_hash_replace(HASH *hash, HASH_SEARCH_STATE *state, uchar *new_row);

=== modified file 'mysys/hash.c'
--- a/mysys/hash.c	2013-09-14 01:09:36 +0000
+++ b/mysys/hash.c	2014-02-14 12:25:41 +0000
@@ -380,6 +380,15 @@ static int hashcmp(const HASH *hash, HAS
 
 my_bool my_hash_insert(HASH *info, const uchar *record)
 {
+  return my_hash_insert_using_hash_value(info, rec_hashnr(info, record),
+                                         record);
+}
+
+
+my_bool my_hash_insert_using_hash_value(HASH *info,
+                                        my_hash_value_type hash_value,
+                                        const uchar *record)
+{
   int flag;
   size_t idx,halfbuff,first_index;
   my_hash_value_type hash_nr;
@@ -480,7 +489,7 @@ my_bool my_hash_insert(HASH *info, const
   }
   /* Check if we are at the empty position */
 
-  idx= my_hash_mask(rec_hashnr(info, record), info->blength, info->records + 1);
+  idx= my_hash_mask(hash_value, info->blength, info->records + 1);
   pos=data+idx;
   if (pos == empty)
   {
@@ -528,6 +537,15 @@ my_bool my_hash_insert(HASH *info, const
 
 my_bool my_hash_delete(HASH *hash, uchar *record)
 {
+  return my_hash_delete_using_hash_value(hash, rec_hashnr(hash, record),
+                                         record);
+}
+
+
+my_bool my_hash_delete_using_hash_value(HASH *hash,
+                                        my_hash_value_type hash_value,
+                                        uchar *record)
+{
   uint pos2,idx,empty_index;
   my_hash_value_type pos_hashnr, lastpos_hashnr;
   size_t blength;
@@ -539,7 +557,7 @@ my_bool my_hash_delete(HASH *hash, uchar
   blength=hash->blength;
   data=dynamic_element(&hash->array,0,HASH_LINK*);
   /* Search after record with key */
-  pos= data + my_hash_mask(rec_hashnr(hash, record), blength, hash->records);
+  pos= data + my_hash_mask(hash_value, blength, hash->records);
   gpos = 0;
 
   while (pos->data != record)

=== modified file 'sql/mdl.cc'
--- a/sql/mdl.cc	2013-12-10 15:31:04 +0000
+++ b/sql/mdl.cc	2014-02-14 12:25:41 +0000
@@ -124,15 +124,9 @@ class MDL_map_partition
 public:
   MDL_map_partition();
   ~MDL_map_partition();
-  inline MDL_lock *find_or_insert(const MDL_key *mdl_key,
-                                  my_hash_value_type hash_value);
-  unsigned long get_lock_owner(const MDL_key *key,
-                               my_hash_value_type hash_value);
+  inline MDL_lock *find_or_insert(const MDL_key *mdl_key);
+  unsigned long get_lock_owner(const MDL_key *key);
   inline void remove(MDL_lock *lock);
-  my_hash_value_type get_key_hash(const MDL_key *mdl_key) const
-  {
-    return my_calc_hash(&m_locks, mdl_key->ptr(), mdl_key->length());
-  }
 private:
   bool move_from_hash_to_lock_mutex(MDL_lock *lock);
   /** A partition of all acquired locks in the server. */
@@ -846,11 +840,10 @@ MDL_lock* MDL_map::find_or_insert(const
     return lock;
   }
 
-  my_hash_value_type hash_value= m_partitions.at(0)->get_key_hash(mdl_key);
-  uint part_id= hash_value % mdl_locks_hash_partitions;
+  uint part_id= mdl_key->hash_value() % mdl_locks_hash_partitions;
   MDL_map_partition *part= m_partitions.at(part_id);
 
-  return part->find_or_insert(mdl_key, hash_value);
+  return part->find_or_insert(mdl_key);
 }
 
 
@@ -863,15 +856,14 @@ MDL_lock* MDL_map::find_or_insert(const
   @retval NULL     - Failure (OOM).
 */
 
-MDL_lock* MDL_map_partition::find_or_insert(const MDL_key *mdl_key,
-                                            my_hash_value_type hash_value)
+MDL_lock* MDL_map_partition::find_or_insert(const MDL_key *mdl_key)
 {
   MDL_lock *lock;
 
 retry:
   mysql_mutex_lock(&m_mutex);
   if (!(lock= (MDL_lock*) my_hash_search_using_hash_value(&m_locks,
-                                                          hash_value,
+                                                          mdl_key->hash_value(),
                                                           mdl_key->ptr(),
                                                           mdl_key->length())))
   {
@@ -902,7 +894,9 @@ MDL_lock* MDL_map_partition::find_or_ins
       lock= MDL_lock::create(mdl_key, this);
     }
 
-    if (!lock || my_hash_insert(&m_locks, (uchar*)lock))
+    if (!lock || my_hash_insert_using_hash_value(&m_locks,
+                                                 mdl_key->hash_value(),
+                                                 (uchar*) lock))
     {
       if (unused_lock)
       {
@@ -1023,10 +1017,9 @@ MDL_map::get_lock_owner(const MDL_key *m
   }
   else
   {
-    my_hash_value_type hash_value= m_partitions.at(0)->get_key_hash(mdl_key);
-    uint part_id= hash_value % mdl_locks_hash_partitions;
+    uint part_id= mdl_key->hash_value() % mdl_locks_hash_partitions;
     MDL_map_partition *part= m_partitions.at(part_id);
-    res= part->get_lock_owner(mdl_key, hash_value);
+    res= part->get_lock_owner(mdl_key);
   }
   return res;
 }
@@ -1034,15 +1027,14 @@ MDL_map::get_lock_owner(const MDL_key *m
 
 
 unsigned long
-MDL_map_partition::get_lock_owner(const MDL_key *mdl_key,
-                                  my_hash_value_type hash_value)
+MDL_map_partition::get_lock_owner(const MDL_key *mdl_key)
 {
   MDL_lock *lock;
   unsigned long res= 0;
 
   mysql_mutex_lock(&m_mutex);
   lock= (MDL_lock*) my_hash_search_using_hash_value(&m_locks,
-                                                  hash_value,
+                                                  mdl_key->hash_value(),
                                                   mdl_key->ptr(),
                                                   mdl_key->length());
   if (lock)
@@ -1085,7 +1077,8 @@ void MDL_map::remove(MDL_lock *lock)
 void MDL_map_partition::remove(MDL_lock *lock)
 {
   mysql_mutex_lock(&m_mutex);
-  my_hash_delete(&m_locks, (uchar*) lock);
+  my_hash_delete_using_hash_value(&m_locks, lock->key.hash_value(),
+                                  (uchar*) lock);
   /*
     To let threads holding references to the MDL_lock object know that it was
     moved to the list of unused objects or destroyed, we increment the version

=== modified file 'sql/mdl.h'
--- a/sql/mdl.h	2013-12-16 08:26:20 +0000
+++ b/sql/mdl.h	2014-02-14 12:25:41 +0000
@@ -347,12 +347,17 @@ class MDL_key
                                           m_ptr - 1);
     m_length= static_cast<uint16>(strmake(m_ptr + m_db_name_length + 2, name,
                                           NAME_LEN) - m_ptr + 1);
+    ulong nr2= 4;
+    m_hash_value= 1;
+    my_charset_bin.coll->hash_sort(&my_charset_bin, (uchar*) m_ptr, m_length,
+                                   &m_hash_value, &nr2);
   }
   void mdl_key_init(const MDL_key *rhs)
   {
     memcpy(m_ptr, rhs->m_ptr, rhs->m_length);
     m_length= rhs->m_length;
     m_db_name_length= rhs->m_db_name_length;
+    m_hash_value= rhs->m_hash_value;
   }
   bool is_equal(const MDL_key *rhs) const
   {
@@ -392,10 +397,15 @@ class MDL_key
   {
     return & m_namespace_to_wait_state_name[(int)mdl_namespace()];
   }
+  ulong hash_value() const
+  {
+    return m_hash_value;
+  }
 
 private:
   uint16 m_length;
   uint16 m_db_name_length;
+  ulong m_hash_value;
   char m_ptr[MAX_MDLKEY_LENGTH];
   static PSI_stage_info m_namespace_to_wait_state_name[NAMESPACE_END];
 private:

=== modified file 'strings/ctype-bin.c'
--- a/strings/ctype-bin.c	2013-11-20 11:05:39 +0000
+++ b/strings/ctype-bin.c	2014-02-14 12:25:41 +0000
@@ -277,7 +277,9 @@ void my_hash_sort_8bit_bin(CHARSET_INFO
                            ulong *nr1, ulong *nr2)
 {
   const uchar *pos = key;
-  
+  ulong tmp1= *nr1;
+  ulong tmp2= *nr2;
+
   /*
      Remove trailing spaces. We have to do this to be able to compare
     'A ' and 'A' as identical
@@ -286,10 +288,13 @@ void my_hash_sort_8bit_bin(CHARSET_INFO
 
   for (; pos < (uchar*) key ; pos++)
   {
-    nr1[0]^=(ulong) ((((uint) nr1[0] & 63)+nr2[0]) * 
-	     ((uint)*pos)) + (nr1[0] << 8);
-    nr2[0]+=3;
+    tmp1^= (ulong) ((((uint) tmp1 & 63) + tmp2) *
+                    ((uint) *pos)) + (tmp1 << 8);
+    tmp2+= 3;
   }
+
+  *nr1= tmp1;
+  *nr2= tmp2;
 }
 
 
@@ -297,15 +302,20 @@ void my_hash_sort_bin(CHARSET_INFO *cs _
 		      const uchar *key, size_t len,ulong *nr1, ulong *nr2)
 {
   const uchar *pos = key;
-  
+  ulong tmp1= *nr1;
+  ulong tmp2= *nr2;
+
   key+= len;
-  
+
   for (; pos < (uchar*) key ; pos++)
   {
-    nr1[0]^=(ulong) ((((uint) nr1[0] & 63)+nr2[0]) * 
-	     ((uint)*pos)) + (nr1[0] << 8);
-    nr2[0]+=3;
+    tmp1^= (ulong) ((((uint) tmp1 & 63) + tmp2) *
+                    ((uint) *pos)) + (tmp1 << 8);
+    tmp2+= 3;
   }
+
+  *nr1= tmp1;
+  *nr2= tmp2;
 }
 
 

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