diff options
| -rw-r--r-- | storage/perfschema/pfs_global.h | 55 | ||||
| -rw-r--r-- | storage/perfschema/pfs_instr.cc | 177 | ||||
| -rw-r--r-- | storage/perfschema/pfs_instr.h | 49 |
3 files changed, 202 insertions, 79 deletions
diff --git a/storage/perfschema/pfs_global.h b/storage/perfschema/pfs_global.h index add1a5d0af6..6050612e24c 100644 --- a/storage/perfschema/pfs_global.h +++ b/storage/perfschema/pfs_global.h @@ -31,27 +31,50 @@ void pfs_free(void *ptr); inline uint randomized_index(const void *ptr, uint max_size) { + static uint seed1= 0; + static uint seed2= 0; + uint result; + register intptr value; + if (unlikely(max_size == 0)) return 0; /* - ptr is typically an aligned structure, - so the last bits are not really random, but this has no effect. - Apply a factor A*x to spread - close values of ptr further apart (which helps with arrays), - and to spread values way beyond a typical max_size. - Then, apply a modulo to end within [0, max_size - 1]. - A is big prime numbers, to avoid resonating with max_size, - to have a uniform distribution in [0, max_size - 1]. - The value of A is chosen so that index(ptr) and index(ptr + N) (for arrays) - are likely to be not similar for typical values of max_size - (50, 100, 1000, etc). - In other words, (sizeof(T)*A % max_size) should not be a small number, - to avoid that with 'T array[max_size]', index(array[i]) - and index(array[i + 1]) end up pointing in the same area in [0, max_size - 1]. + ptr is typically an aligned structure, and can be in an array. + - The last bits are not random because of alignment, + so we divide by 8. + - The high bits are mostly constant, especially with 64 bits architectures, + but we keep most of them anyway, by doing computation in intptr. + The high bits are significant depending on where the data is + stored (the data segment, the stack, the heap, ...). + - To spread consecutive cells in an array further, we multiply by + a factor A. This factor should not be too high, which would cause + an overflow and cause loss of randomness (droping the top high bits). + The factor is a prime number, to help spread the distribution. + - To add more noise, and to be more robust if the calling code is + passing a constant value instead of a random identity, + we add the previous results, for hysteresys, with a degree 2 polynom, + X^2 + X + 1. + - Last, a modulo is applied to be within the [0, max_size - 1] range. + Note that seed1 and seed2 are static, and are *not* thread safe, + which is even better. + Effect with arrays: T array[N] + - ptr(i) = & array[i] = & array[0] + i * sizeof(T) + - ptr(i+1) = ptr(i) + sizeof(T). + What we want here, is to have index(i) and index(i+1) fall into + very different areas in [0, max_size - 1], to avoid locality. */ - return static_cast<uint> - (((reinterpret_cast<intptr> (ptr)) * 2166179) % max_size); + value= (reinterpret_cast<intptr> (ptr)) >> 3; + value*= 1789; + value+= seed2 + seed1 + 1; + + result= (static_cast<uint> (value)) % max_size; + + seed2= seed1*seed1; + seed1= result; + + DBUG_ASSERT(result < max_size); + return result; } void pfs_print_error(const char *format, ...); diff --git a/storage/perfschema/pfs_instr.cc b/storage/perfschema/pfs_instr.cc index 9507e2d2582..3071df17325 100644 --- a/storage/perfschema/pfs_instr.cc +++ b/storage/perfschema/pfs_instr.cc @@ -1,4 +1,4 @@ -/* Copyright (C) 2008-2009 Sun Microsystems, Inc +/* Copyright (c) 2008, 2010 Oracle and/or its affiliates. All rights reserved. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -10,8 +10,8 @@ GNU General Public License for more details. You should have received a copy of the GNU General Public License - along with this program; if not, write to the Free Software - Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ + along with this program; if not, write to the Free Software Foundation, + 51 Franklin Street, Suite 500, Boston, MA 02110-1335 USA */ /** @file storage/perfschema/pfs_instr.cc @@ -21,8 +21,8 @@ #include <string.h> #include "my_global.h" -#include "sql_priv.h" #include "my_sys.h" +#include "pfs.h" #include "pfs_stat.h" #include "pfs_instr.h" #include "pfs_global.h" @@ -411,6 +411,8 @@ void cleanup_instruments(void) thread_instr_class_waits_array= NULL; } +extern "C" +{ static uchar *filename_hash_get_key(const uchar *entry, size_t *length, my_bool) { @@ -425,6 +427,7 @@ static uchar *filename_hash_get_key(const uchar *entry, size_t *length, result= file->m_filename; return const_cast<uchar*> (reinterpret_cast<const uchar*> (result)); } +} /** Initialize the file name hash. @@ -451,6 +454,75 @@ void cleanup_file_hash(void) } } +void PFS_scan::init(uint random, uint max_size) +{ + m_pass= 0; + + if (max_size == 0) + { + /* Degenerated case, no buffer */ + m_pass_max= 0; + return; + } + + DBUG_ASSERT(random < max_size); + + if (PFS_MAX_ALLOC_RETRY < max_size) + { + /* + The buffer is big compared to PFS_MAX_ALLOC_RETRY, + scan it only partially. + */ + if (random + PFS_MAX_ALLOC_RETRY < max_size) + { + /* + Pass 1: [random, random + PFS_MAX_ALLOC_RETRY - 1] + Pass 2: not used. + */ + m_pass_max= 1; + m_first[0]= random; + m_last[0]= random + PFS_MAX_ALLOC_RETRY; + m_first[1]= 0; + m_last[1]= 0; + } + else + { + /* + Pass 1: [random, max_size - 1] + Pass 2: [0, ...] + The combined length of pass 1 and 2 is PFS_MAX_ALLOC_RETRY. + */ + m_pass_max= 2; + m_first[0]= random; + m_last[0]= max_size; + m_first[1]= 0; + m_last[1]= PFS_MAX_ALLOC_RETRY - (max_size - random); + } + } + else + { + /* + The buffer is small compared to PFS_MAX_ALLOC_RETRY, + scan it in full in two passes. + Pass 1: [random, max_size - 1] + Pass 2: [0, random - 1] + */ + m_pass_max= 2; + m_first[0]= random; + m_last[0]= max_size; + m_first[1]= 0; + m_last[1]= random; + } + + DBUG_ASSERT(m_first[0] < max_size); + DBUG_ASSERT(m_first[1] < max_size); + DBUG_ASSERT(m_last[1] <= max_size); + DBUG_ASSERT(m_last[1] <= max_size); + /* The combined length of all passes should not exceed PFS_MAX_ALLOC_RETRY. */ + DBUG_ASSERT((m_last[0] - m_first[0]) + + (m_last[1] - m_first[1]) <= PFS_MAX_ALLOC_RETRY); +} + /** Create instrumentation for a mutex instance. @param klass the mutex class @@ -459,17 +531,15 @@ void cleanup_file_hash(void) */ PFS_mutex* create_mutex(PFS_mutex_class *klass, const void *identity) { - int pass; - uint i= randomized_index(identity, mutex_max); + PFS_scan scan; + uint random= randomized_index(identity, mutex_max); - /* - Pass 1: [random, mutex_max - 1] - Pass 2: [0, mutex_max - 1] - */ - for (pass= 1; pass <= 2; i=0, pass++) + for (scan.init(random, mutex_max); + scan.has_pass(); + scan.next_pass()) { - PFS_mutex *pfs= mutex_array + i; - PFS_mutex *pfs_last= mutex_array + mutex_max; + PFS_mutex *pfs= mutex_array + scan.first(); + PFS_mutex *pfs_last= mutex_array + scan.last(); for ( ; pfs < pfs_last; pfs++) { if (pfs->m_lock.is_free()) @@ -517,17 +587,15 @@ void destroy_mutex(PFS_mutex *pfs) */ PFS_rwlock* create_rwlock(PFS_rwlock_class *klass, const void *identity) { - int pass; - uint i= randomized_index(identity, rwlock_max); + PFS_scan scan; + uint random= randomized_index(identity, rwlock_max); - /* - Pass 1: [random, rwlock_max - 1] - Pass 2: [0, rwlock_max - 1] - */ - for (pass= 1; pass <= 2; i=0, pass++) + for (scan.init(random, rwlock_max); + scan.has_pass(); + scan.next_pass()) { - PFS_rwlock *pfs= rwlock_array + i; - PFS_rwlock *pfs_last= rwlock_array + rwlock_max; + PFS_rwlock *pfs= rwlock_array + scan.first(); + PFS_rwlock *pfs_last= rwlock_array + scan.last(); for ( ; pfs < pfs_last; pfs++) { if (pfs->m_lock.is_free()) @@ -581,17 +649,15 @@ void destroy_rwlock(PFS_rwlock *pfs) */ PFS_cond* create_cond(PFS_cond_class *klass, const void *identity) { - int pass; - uint i= randomized_index(identity, cond_max); + PFS_scan scan; + uint random= randomized_index(identity, cond_max); - /* - Pass 1: [random, cond_max - 1] - Pass 2: [0, cond_max - 1] - */ - for (pass= 1; pass <= 2; i=0, pass++) + for (scan.init(random, cond_max); + scan.has_pass(); + scan.next_pass()) { - PFS_cond *pfs= cond_array + i; - PFS_cond *pfs_last= cond_array + cond_max; + PFS_cond *pfs= cond_array + scan.first(); + PFS_cond *pfs_last= cond_array + scan.last(); for ( ; pfs < pfs_last; pfs++) { if (pfs->m_lock.is_free()) @@ -639,17 +705,15 @@ void destroy_cond(PFS_cond *pfs) PFS_thread* create_thread(PFS_thread_class *klass, const void *identity, ulong thread_id) { - int pass; - uint i= randomized_index(identity, thread_max); + PFS_scan scan; + uint random= randomized_index(identity, thread_max); - /* - Pass 1: [random, thread_max - 1] - Pass 2: [0, thread_max - 1] - */ - for (pass= 1; pass <= 2; i=0, pass++) + for (scan.init(random, thread_max); + scan.has_pass(); + scan.next_pass()) { - PFS_thread *pfs= thread_array + i; - PFS_thread *pfs_last= thread_array + thread_max; + PFS_thread *pfs= thread_array + scan.first(); + PFS_thread *pfs_last= thread_array + scan.last(); for ( ; pfs < pfs_last; pfs++) { if (pfs->m_lock.is_free()) @@ -733,7 +797,7 @@ find_or_create_file(PFS_thread *thread, PFS_file_class *klass, const char *filename, uint len) { PFS_file *pfs; - int pass; + PFS_scan scan; if (! filename_hash_inited) { @@ -806,17 +870,14 @@ search: } /* filename is not constant, just using it for noise on create */ - uint i= randomized_index(filename, file_max); + uint random= randomized_index(filename, file_max); - /* - Pass 1: [random, file_max - 1] - Pass 2: [0, file_max - 1] - */ - for (pass= 1; pass <= 2; i=0, pass++) + for (scan.init(random, file_max); + scan.has_pass(); + scan.next_pass()) { - pfs= file_array + i; - PFS_file *pfs_last= file_array + file_max; - + pfs= file_array + scan.first(); + PFS_file *pfs_last= file_array + scan.last(); for ( ; pfs < pfs_last; pfs++) { if (pfs->m_lock.is_free()) @@ -901,17 +962,15 @@ void destroy_file(PFS_thread *thread, PFS_file *pfs) */ PFS_table* create_table(PFS_table_share *share, const void *identity) { - int pass; - uint i= randomized_index(identity, table_max); + PFS_scan scan; + uint random= randomized_index(identity, table_max); - /* - Pass 1: [random, table_max - 1] - Pass 2: [0, table_max - 1] - */ - for (pass= 1; pass <= 2; i=0, pass++) + for (scan.init(random, table_max); + scan.has_pass(); + scan.next_pass()) { - PFS_table *pfs= table_array + i; - PFS_table *pfs_last= table_array + table_max; + PFS_table *pfs= table_array + scan.first(); + PFS_table *pfs_last= table_array + scan.last(); for ( ; pfs < pfs_last; pfs++) { if (pfs->m_lock.is_free()) diff --git a/storage/perfschema/pfs_instr.h b/storage/perfschema/pfs_instr.h index a509d054d69..791e2cd1f8d 100644 --- a/storage/perfschema/pfs_instr.h +++ b/storage/perfschema/pfs_instr.h @@ -1,4 +1,4 @@ -/* Copyright (C) 2008-2009 Sun Microsystems, Inc +/* Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -10,8 +10,8 @@ GNU General Public License for more details. You should have received a copy of the GNU General Public License - along with this program; if not, write to the Free Software - Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ + along with this program; if not, write to the Free Software Foundation, + 51 Franklin Street, Suite 500, Boston, MA 02110-1335 USA */ #ifndef PFS_INSTR_H #define PFS_INSTR_H @@ -21,7 +21,6 @@ Performance schema instruments (declarations). */ -#include <sql_priv.h> #include "pfs_lock.h" #include "pfs_instr_class.h" #include "pfs_events_waits.h" @@ -136,6 +135,48 @@ struct PFS_table : public PFS_instr */ #define LOCKER_STACK_SIZE 3 +/** + @def PFS_MAX_ALLOC_RETRY + Maximum number of times the code attempts to allocate an item + from internal buffers, before giving up. +*/ +#define PFS_MAX_ALLOC_RETRY 1000 + +#define PFS_MAX_SCAN_PASS 2 + +/** + Helper to scan circular buffers. + Given a buffer of size [0, max_size - 1], + and a random starting point in the buffer, + this helper returns up to two [first, last -1] intervals that: + - fit into the [0, max_size - 1] range, + - have a maximum combined length of at most PFS_MAX_ALLOC_RETRY. +*/ +struct PFS_scan +{ +public: + void init(uint random, uint max_size); + + bool has_pass() const + { return (m_pass < m_pass_max); } + + void next_pass() + { m_pass++; } + + uint first() const + { return m_first[m_pass]; } + + uint last() const + { return m_last[m_pass]; } + +private: + uint m_pass; + uint m_pass_max; + uint m_first[PFS_MAX_SCAN_PASS]; + uint m_last[PFS_MAX_SCAN_PASS]; +}; + + /** Instrumented thread implementation. @see PSI_thread. */ struct PFS_thread { |