查看Oracle 10gR2 10205 RAC CPU负载过高问题的源代码

==现象1==
/u01/app/oracle/admin/TBNLOT/udump/tbnlot2_ora_1610.trc
Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bit Production
With the Partitioning, Real Application Clusters, OLAP, Data Mining
and Real Application Testing options
ORACLE_HOME = /u01/app/oracle/product/10.2.0/db_1
System name:    Linux
Node name:      nrac2
Release:        2.6.18-371.11.1.el5
Version:        #1 SMP Wed Jul 23 15:12:55 EDT 2014
Machine:        x86_64
Instance name: TBNLOT2
Redo thread mounted by this instance: 2
Oracle process number: 465
Unix process pid: 1610, image: oracle@nrac2

*** ACTION NAME:() 2014-09-29 15:06:32.377
*** MODULE NAME:(TCPrintAppServer.exe) 2014-09-29 15:06:32.377
*** SERVICE NAME:(TBNLOTT) 2014-09-29 15:06:32.377
*** SESSION ID:(845.3) 2014-09-29 15:06:32.377
WARNING:io_submit failed due to kernel limitations MAXAIO for process=0 pending aio=0
WARNING:asynch I/O kernel limits is set at AIO-MAX-NR=65536 AIO-NR=65516
WARNING:1 Oracle process running out of OS kernelI/O resources aiolimit=0
ksfdgo()+1488<-ksfdaio1()+9848<-kfkUfsIO()+594<-kfkDoIO()+631<-kfkIOPriv()+616<-kfdIOPriv()+95<-kfioSubmitIO()+503<-kfioRequestPriv()+166<-kfioRequest()+689<-ksfd_osmgo()+1286<-ksfdgo()+1488<-ksfdaio1()+9848<-kcflbi()+498<-kcbldio()+1897<-kcblrs()+357<-kcblrd()+154
<-kcblgt()+1215<-kcbldrget()+218<-kcbgtcr()+25990<-kdlrdb()+146<-kdlccbk()+355<-kdlwfb()+716<-kdl_write1()+2399<-kdl_copy()+972ssd_unwind_bp: unhandled instruction at 0x1f01b1f instr=f
<-kokliclo()+565<-koklcre()+512<-kokleva()+863<-evaopn2()+458<-insolev()+196<-insbrp()+360<-insrow()+236<-insdrv()+589<-inscovexe()+399<-insExecStmtExecIniEngine()+85<-insexe()+384<-opiexe()+9334<-kpoal8()+2295<-opiodr()+1184<-ttcpip()+1226<-opitsk()+1310<-opiino()+1024
<-opiodr()+1184<-opidrv()+548<-sou2o()+114<-opimai_real()+163<-main()+116<-__libc_start_main()+244<-_start()+41

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND                                                                            
 9407 oracle    25   0 32.2g  59m  51m R 99.9  0.0 944:57.20 oracle                                                                              
24494 oracle    25   0 32.1g  30m  23m R 99.9  0.0  53:47.66 oracle                                                                              
27200 oracle    25   0 32.1g  46m  39m R 99.9  0.0   1156:21 oracle                                                                              
30885 oracle    25   0 32.1g  30m  23m R 99.9  0.0 103:06.92 oracle                                                                              
31073 oracle    25   0 32.1g  30m  23m R 99.9  0.0 102:45.68 oracle   
==现象2==
/u01/app/oracle/admin/TBNLOT/udump/tbnlot1_ora_14007.trc
Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bit Production
With the Partitioning, Real Application Clusters, OLAP, Data Mining
and Real Application Testing options
ORACLE_HOME = /u01/app/oracle/product/10.2.0/db_1
System name:	Linux
Node name:	nrac1
Release:	2.6.18-371.11.1.el5
Version:	#1 SMP Wed Jul 23 15:12:55 EDT 2014
Machine:	x86_64
Instance name: TBNLOT1
Redo thread mounted by this instance: 0 <none>
Oracle process number: 0
Unix process pid: 14007, image: oracle@nrac1

Number of resource hash buckets is 6955
Parsing user specified table space list to be ignored
2014-09-29 15:12:21.689: [ COMMCRS]clsc_set_clsd_NS_trace: called before init completed
Number of resource hash buckets is 6955
* kjfcnfy: kjinumbuckets = 32768 
Dynamic strand is set to TRUE
Running with 2 shared and 0 private strand(s). Zero-copy redo is FALSE

查了查资料，又说是bug，但给出了两种解决方法：一，增加操作系统内核参数AIO-MAX-NR的值；二，禁用磁盘AIO机制。我采用了修改系统内核参数AIO-MAX-NR的方法来解决这个问题。
1、可以临时修改内核参数aio-max-nr
# echo > /proc/sys/fs/aio-max-nr 1048576
2、永久修改内核参数aio-max-nr，需要在/etc/sysctl.conf加上下面这句
fs.aio-max-nr = 1048576
用下列命令使参数生效
#/sbin/sysctl -p

==解决办法==
附，参考资料
Bug 9949948 Linux: Process spin under ksfdrwat0 if OS Async IO not configured high enough
This note gives a brief overview of bug 9949948. 
The content was last updated on: 28-OCT-2011
Click here for details of each of the sections below.
Affects:
Product (Component) Oracle Server (Rdbms)
Range of versions believed to be affected Versions >= 10.2.0.4 but BELOW 11.1
Versions confirmed as being affected 
10.2.0.5
Platforms affected 
Linux X86-64bit
Linux 32bit
It is believed to be a regression in default behaviour thus:
Regression introduced in 10.2.0.5
Fixed:
This issue is fixed in 
11.1.0.6 (Base Release)
10.2.0.5.2 Patch Set Update
10.2.0.5 Patch 5 on Windows Platforms
Symptoms:
Related To:
Hang (Process Spins)
Waits for "i/o slave wait"
DISK_ASYNCH_IO
Description
This problem is introduced in 10.2.0.5 

It only affects platforms where Oracle has to reserve async IO slots, 
such as Linux platforms.

If the OS async IO layer is underconfigured and an Oracle process
cannot get sufficient AIO slots then rather than reverting to 
using non AIO call the process may go into an infinite spin
under ksfdrwat0.

Rediscovery notes:
The spin will be preceded by messages in the trace 
file of the form:
WARNING:io_submit failed due to kernel limitations MAXAIO 
for process=0 pending aio=0
WARNING:asynch I/O kernel limits is set at AIO-MAX-NR=65536 AIO-NR=65518
WARNING:1 Oracle process running out of OS kernelI/O resources aiolimit=0

Notice specifically that the value for aiolimit is reported as "0" 
for this bug.

The process then spins in ksfdrwat0 typically with a stack showing
skgfqio ()
ksfdgo ()
ksfdwtio ()
ksfdwat1 ()
ksfdrwat0 () <<< Spin point
ksfdblock ()
kcflwi ()
kcflci ()
kcblci ()
kcblcio ()
kcblgt ()
kcbldrget ()

It will show repeated waits for "i/o slave wait", which can be
misleading as that is normally considered an idle wait event.

Workaround
Raise the OS AIO limits such that the number of concurrent slot
requirements never exceeds the OS limit.
ie: Increase AIO-MAX-NR
OR
Disable async IO (Set DISK_ASYNCH_IO=FALSE)

See Note:1313555.1 for additional notes on this issue.
Please note: The above is a summary description only. Actual symptoms can vary. Matching to any symptoms here does not confirm that you are encountering this problem. For questions about this bug please consult Oracle Support.
References
Bug:9949948 (This link will only work for PUBLISHED bugs)
Note:245840.1 Information on the sections in this article