Hi,

I have an Oracle 8.1.7.4 64bit running in a Solaris 9 branded zone on-top of 
Solaris 10.
When I put a tablespace in a hotbackup mode it takes long time - usually more 
than 4s for each tablespace. Looks like ora_ckpt process is consuming 100% of 
cpu (in usr) while a tablespace is being put in the hotbackup mode.

It looks like there might be an issue with semop() interposition in S9 branded 
zone.
I can't easily test it now but IIRC when running Oracle in a global zone there 
was no such issue.

More details below.

First, lets check a PID of ora_ckpt

# ps -ef | grep 20326
  oracle 20326     1   0 15:37:26 ?          15:52 ora_ckpt_I321

Now lets put a TEMP tablespace in a backup mode while running a dtrace script 
as well:

SQL> alter tablespace TEMP begin backup;

Tablespace altered.

Elapsed: 00:00:04.65



# dtrace -n sched:::on-cpu'/pid==20326 && tid==1/{self->t=timestamp;}' -n 
sched:::off-cpu'/self->t/{...@u[ustack()]=sum(timestamp-self->t);@c[ustack()]=count();self->t=0;}'
 -n tick-10s'{printa(@u);printa(@c)}'
dtrace: description 'sched:::on-cpu' matched 1 probe
dtrace: description 'sched:::off-cpu' matched 2 probes
dtrace: description 'tick-10s' matched 1 probe
^C


              `_s9brand_systemcall+0x30
              `s9_semsys+0x16c
              `s9_handler+0x84
              oracle`sslssalck+0x514
              libc.so.1`semop+0x18
              oracle`sskgpwwait+0x13c
              oracle`ksliwat+0x44c
              oracle`kslwaitns+0x20
              oracle`kskthbwt+0x174
              oracle`kslwait+0x50
              oracle`ksarcv+0x1bc
              oracle`ksbabs+0x344
              oracle`ksbrdp+0x2ec
              oracle`opirip+0x31c
              oracle`opidrv+0x6a0
              oracle`sou2o+0x10
              oracle`main+0x128
              oracle`_start+0x17c
              oracle`_start+0x18
       3852868427

              oracle`_s9brand_systemcall+0x30
              oracle`s9_semsys+0x16c
              oracle`s9_handler+0x84
              oracle`sslssalck+0x514
              libc.so.1`semop+0x18
              oracle`sskgpwwait+0x13c
              oracle`ksliwat+0x44c
              oracle`kslwaitns+0x20
              oracle`kskthbwt+0x174
              oracle`kslwait+0x50
              oracle`ksarcv+0x1bc
              oracle`ksbabs+0x344
              oracle`ksbrdp+0x2ec
              oracle`opirip+0x31c
              oracle`opidrv+0x6a0
              oracle`sou2o+0x10
              oracle`main+0x128
              oracle`_start+0x17c
              oracle`_start+0x18
               12

So the same ustack() consumed almost 4s of a CPU time out of 4.6s of a total 
time of the operation.

Has anyone been hit by it?

Also the 2nd stack looks strange (top 5 lines)...

-- 
Robert Milkowski
http://milek.blogspot.com
-- 
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