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How to discover 'OS waits' reason?

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  • How to discover 'OS waits' reason?

    Hi,
    Sometimes my server freezes for a minute. INNODB STATUS 'OS waits' significantly rises at these moments, please see the graph.

    Attachment

    PROCESSLIST shows much 'updating' and 'query end' sessions as well.

    Attachment

    How to discover the reason of OS waits rise?

    CentOS 6
    Percona-Server-server-55-5.5.16

  • #2
    Below are semaphores from INNODB STATUS. Could it help to reduce OS waits?

    Code:
    --Thread 139899316999936 has waited at btr0cur.c line 553 for 0.0000 seconds the semaphore:
    S-lock on RW-latch at 0x35780ba8 '&new_index->lock'
    a writer (thread id 139899306510080) has reserved it in mode  exclusive
    number of readers 0, waiters flag 1, lock_word: fffffffffff00000
    Last time read locked in file btr0cur.c line 553
    Last time write locked in file /home/ignacio.nin/src/work/BUILD/Percona-Server-5.5.16-rel22.0/Percona-Server-5.5.16-rel2
    2.0/storage/innobase/ibuf/ibuf0ibuf.c line 400
    --Thread 139939654498048 has waited at lock0lock.c line 3919 for 0.0000 seconds the semaphore:
    Mutex at 0x1820818 '&kernel_mutex', lock var 1
    waiters flag 1
    --Thread 139939671557888 has waited at row0sel.c line 3079 for 0.0000 seconds the semaphore:
    S-lock on RW-latch at 0x7f3d20b38ef8 '&block->lock'
    a writer (thread id 139899201611520) has reserved it in mode  wait exclusive
    number of readers 8, waiters flag 1, lock_word: fffffffffffffff8
    Last time read locked in file row0sel.c line 3079
    Last time write locked in file /home/ignacio.nin/src/work/BUILD/Percona-Server-5.5.16-rel22.0/Percona-Server-5.5.16-rel2
    2.0/storage/innobase/btr/btr0cur.c line 286
    --Thread 139939646269184 has waited at trx0trx.c line 1772 for 0.0000 seconds the semaphore:
    Mutex at 0x1820818 '&kernel_mutex', lock var 0
    waiters flag 0
    --Thread 139939659716352 has waited at lock0lock.c line 5453 for 0.0000 seconds the semaphore:
    Mutex at 0x1820818 '&kernel_mutex', lock var 0
    waiters flag 0
    --Thread 139939674568448 has waited at lock0lock.c line 3919 for 0.0000 seconds the semaphore:
    Mutex at 0x1820818 '&kernel_mutex', lock var 0
    waiters flag 0
    --Thread 139939679786752 has waited at lock0lock.c line 3919 for 0.0000 seconds the semaphore:
    Mutex at 0x1820818 '&kernel_mutex', lock var 1
    waiters flag 0
    --Thread 139899306510080 has waited at lock0lock.c line 3203 for 0.0000 seconds the semaphore:
    Mutex at 0x1820818 '&kernel_mutex', lock var 0
    waiters flag 0
    --Thread 139939679586048 has waited at lock0lock.c line 3919 for 0.0000 seconds the semaphore:
    Mutex at 0x1820818 '&kernel_mutex', lock var 0
    waiters flag 0
    --Thread 139939666138880 has waited at lock0lock.c line 3919 for 0.0000 seconds the semaphore:
    Mutex at 0x1820818 '&kernel_mutex', lock var 0
    waiters flag 0
    --Thread 139939655702272 has waited at lock0lock.c line 5453 for 0.0000 seconds the semaphore:
    Mutex at 0x1820818 '&kernel_mutex', lock var 0
    waiters flag 0
    --Thread 139899201611520 has waited at row0row.c line 801 for 0.0000 seconds the semaphore:
    X-lock (wait_ex) on RW-latch at 0x7f3d20b38ef8 '&block->lock'
    a writer (thread id 139899201611520) has reserved it in mode  wait exclusive
    number of readers 7, waiters flag 1, lock_word: fffffffffffffff9
    Last time read locked in file row0sel.c line 3079
    Last time write locked in file /home/ignacio.nin/src/work/BUILD/Percona-Server-5.5.16-rel22.0/Percona-Server-5.5.16-rel22.0/storage/innobase/btr/btr0cur.c line 286
    --Thread 139939678783232 has waited at trx0trx.c line 795 for 0.0000 seconds the semaphore:
    Mutex at 0x1820818 '&kernel_mutex', lock var 0
    waiters flag 0
    --Thread 139939674167040 has waited at lock0lock.c line 3919 for 0.0000 seconds the semaphore:
    Mutex at 0x1820818 '&kernel_mutex', lock var 0
    waiters flag 0
    --Thread 139939650885376 has waited at lock0lock.c line 3919 for 0.0000 seconds the semaphore:
    Mutex at 0x1820818 '&kernel_mutex', lock var 0
    waiters flag 0
    --Thread 139939651487488 has waited at lock0lock.c line 3919 for 0.0000 seconds the semaphore:
    Mutex at 0x1820818 '&kernel_mutex', lock var 0
    waiters flag 0
    --Thread 139939644262144 has waited at lock0lock.c line 3919 for 0.0000 seconds the semaphore:
    Mutex at 0x1820818 '&kernel_mutex', lock var 0
    waiters flag 0
    --Thread 139939668145920 has waited at lock0lock.c line 3919 for 0.0000 seconds the semaphore:
    Mutex at 0x1820818 '&kernel_mutex', lock var 0
    waiters flag 0
    --Thread 139899327489792 has waited at lock0lock.c line 3203 for 0.0000 seconds the semaphore:
    Mutex at 0x1820818 '&kernel_mutex', lock var 0
    waiters flag 0
    --Thread 139939662526208 has waited at row0vers.c line 123 for 0.0000 seconds the semaphore:
    Mutex at 0x1820818 '&kernel_mutex', lock var 0
    waiters flag 0
    --Thread 139939675170560 has waited at trx0trx.c line 795 for 0.0000 seconds the semaphore:
    Mutex at 0x1820818 '&kernel_mutex', lock var 0
    waiters flag 0

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