#At file:///home/malff/BZR_TREE/mysql-trunk-bugfixing-55462/ based on revid:jonathan.perkin@stripped
3133 Marc Alff 2010-07-21
Bug#55462 Performance schema: reduce the overhead of PFS_events_waits::m_wait_class
This is a performance improvement fix.
Removed the "volatile" property of PFS_events_waits::m_wait_class.
Simplified the code accordingly.
modified:
storage/perfschema/pfs.cc
storage/perfschema/pfs_events_waits.cc
storage/perfschema/pfs_events_waits.h
storage/perfschema/table_events_waits.cc
=== modified file 'storage/perfschema/pfs.cc'
--- a/storage/perfschema/pfs.cc 2010-07-15 23:44:45 +0000
+++ b/storage/perfschema/pfs.cc 2010-07-22 00:58:31 +0000
@@ -1117,7 +1117,6 @@ get_thread_mutex_locker_v1(PSI_mutex_loc
}
PFS_wait_locker *pfs_locker= &pfs_thread->m_wait_locker_stack
[pfs_thread->m_wait_locker_count];
- pfs_locker->m_waits_current.m_wait_class= NO_WAIT_CLASS;
pfs_locker->m_target.m_mutex= pfs_mutex;
pfs_locker->m_waits_current.m_thread= pfs_thread;
@@ -1163,7 +1162,6 @@ get_thread_rwlock_locker_v1(PSI_rwlock_l
}
PFS_wait_locker *pfs_locker= &pfs_thread->m_wait_locker_stack
[pfs_thread->m_wait_locker_count];
- pfs_locker->m_waits_current.m_wait_class= NO_WAIT_CLASS;
pfs_locker->m_target.m_rwlock= pfs_rwlock;
pfs_locker->m_waits_current.m_thread= pfs_thread;
@@ -1222,7 +1220,6 @@ get_thread_cond_locker_v1(PSI_cond_locke
}
PFS_wait_locker *pfs_locker= &pfs_thread->m_wait_locker_stack
[pfs_thread->m_wait_locker_count];
- pfs_locker->m_waits_current.m_wait_class= NO_WAIT_CLASS;
pfs_locker->m_target.m_cond= pfs_cond;
pfs_locker->m_waits_current.m_thread= pfs_thread;
@@ -1267,7 +1264,6 @@ get_thread_table_locker_v1(PSI_table_loc
}
PFS_wait_locker *pfs_locker= &pfs_thread->m_wait_locker_stack
[pfs_thread->m_wait_locker_count];
- pfs_locker->m_waits_current.m_wait_class= NO_WAIT_CLASS;
pfs_locker->m_target.m_table= pfs_table;
pfs_locker->m_waits_current.m_thread= pfs_thread;
@@ -1320,7 +1316,6 @@ get_thread_file_name_locker_v1(PSI_file_
PFS_wait_locker *pfs_locker= &pfs_thread->m_wait_locker_stack
[pfs_thread->m_wait_locker_count];
- pfs_locker->m_waits_current.m_wait_class= NO_WAIT_CLASS;
pfs_locker->m_target.m_file= pfs_file;
pfs_locker->m_waits_current.m_thread= pfs_thread;
@@ -1372,7 +1367,6 @@ get_thread_file_stream_locker_v1(PSI_fil
}
PFS_wait_locker *pfs_locker= &pfs_thread->m_wait_locker_stack
[pfs_thread->m_wait_locker_count];
- pfs_locker->m_waits_current.m_wait_class= NO_WAIT_CLASS;
pfs_locker->m_target.m_file= pfs_file;
pfs_locker->m_waits_current.m_thread= pfs_thread;
@@ -1441,7 +1435,6 @@ get_thread_file_descriptor_locker_v1(PSI
}
PFS_wait_locker *pfs_locker= &pfs_thread->m_wait_locker_stack
[pfs_thread->m_wait_locker_count];
- pfs_locker->m_waits_current.m_wait_class= NO_WAIT_CLASS;
pfs_locker->m_target.m_file= pfs_file;
pfs_locker->m_waits_current.m_thread= pfs_thread;
=== modified file 'storage/perfschema/pfs_events_waits.cc'
--- a/storage/perfschema/pfs_events_waits.cc 2010-07-15 23:44:45 +0000
+++ b/storage/perfschema/pfs_events_waits.cc 2010-07-22 00:58:31 +0000
@@ -81,26 +81,10 @@ void cleanup_events_waits_history_long(v
events_waits_history_long_array= NULL;
}
-static void copy_events_waits(PFS_events_waits *dest,
- const PFS_events_waits *source)
+static inline void copy_events_waits(PFS_events_waits *dest,
+ const PFS_events_waits *source)
{
- /* m_wait_class must be the first member of PFS_events_waits. */
- compile_time_assert(offsetof(PFS_events_waits, m_wait_class) == 0);
-
- char* dest_body= (reinterpret_cast<char*> (dest)) + sizeof(events_waits_class);
- const char* source_body= (reinterpret_cast<const char*> (source))
- + sizeof(events_waits_class);
-
- /* See comments in table_events_waits_common::make_row(). */
-
- /* Signal readers they are about to read garbage ... */
- dest->m_wait_class= NO_WAIT_CLASS;
- /* ... that this can generate. */
- memcpy_fixed(dest_body,
- source_body,
- sizeof(PFS_events_waits) - sizeof(events_waits_class));
- /* Signal readers the record is now clean again. */
- dest->m_wait_class= source->m_wait_class;
+ memcpy_fixed(dest, source, sizeof(PFS_events_waits));
}
/**
@@ -118,9 +102,7 @@ void insert_events_waits_history(PFS_thr
causing a potential race condition.
We are not testing for this and insert a possibly empty record,
to make this thread (the writer) faster.
- This is ok, the truncated data will have
- wait->m_wait_class == NO_WAIT_CLASS,
- which readers of m_waits_history will filter out.
+ This is ok, the readers of m_waits_history will filter this out.
*/
copy_events_waits(&thread->m_waits_history[index], wait);
=== modified file 'storage/perfschema/pfs_events_waits.h'
--- a/storage/perfschema/pfs_events_waits.h 2010-07-15 23:44:45 +0000
+++ b/storage/perfschema/pfs_events_waits.h 2010-07-22 00:58:31 +0000
@@ -97,7 +97,7 @@ struct PFS_events_waits
- TRUNCATE EVENTS_WAITS_HISTORY
- TRUNCATE EVENTS_WAITS_HISTORY_LONG
*/
- volatile events_waits_class m_wait_class;
+ events_waits_class m_wait_class;
/** Executing thread. */
PFS_thread *m_thread;
/** Instrument metadata. */
=== modified file 'storage/perfschema/table_events_waits.cc'
--- a/storage/perfschema/table_events_waits.cc 2010-07-16 00:06:33 +0000
+++ b/storage/perfschema/table_events_waits.cc 2010-07-22 00:58:31 +0000
@@ -217,16 +217,8 @@ void table_events_waits_common::make_row
or 8 atomics per recorded event.
The problem is that we record a *lot* of events ...
- Instead, a *dirty* marking is done using m_wait_class.
- Using m_wait_class alone does not guarantee anything, it just filters
- out most of the bad data.
- This is acceptable because this code is garbage-proof,
- and won't crash on bad data, only display it,
- very rarely (which is accepted).
-
- If a bad record is displayed, it's a very transient failure:
- the next select * from EVENTS_WAITS_CURRENT/_HISTORY/_HISTORY_LONG will
- show clean data again.
+ This code is prepared to accept *dirty* records,
+ and sanitizes all the data before returning a row.
*/
m_row.m_thread_internal_id= safe_thread->m_thread_internal_id;
Attachment: [text/bzr-bundle] bzr/marc.alff@oracle.com-20100722005831-6lo9dsydgc590fi1.bundle
