pagecache and hugetlb tuning for Oracle DB operations

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pagecache and hugetlb tuning for Oracle DB operations

pagecache and hugetlb tuning for Oracle DB operations

2006-06-09 - By David.Knight@(protected)

Back

Reply: 1 2 3 4 5 6 7

Have you enabled direct I/O or AIO for Oracle and Linux?
http://www.rampant-books.com/t_oracle_direct_i_o.htm

We run the same exact Oracle/Linux/Hardware configuration here and don't
have that issue. You may also make use of the sync or update commands like
people do on Unix systems.
What does `cat /proc/meminfo` show?

-David Knight

"Jim Williams" <Jim.Williams@(protected)>
Sent by: taroon-list-bounces@(protected)
06/09/2006 02:58 PM
Please respond to
"Discussion of Red Hat Enterprise Linux 3 (Taroon)"
<taroon-list@(protected)>

To
taroon-list@(protected)
cc

Subject
pagecache and hugetlb tuning for Oracle DB operations

I am managing a new server configuration to support Oracle 9i v 9.2.0. The
SGA is approximately 7 GB and we are running on a pair of new HP DL585?s
with 4 dual-core Opteron CPU?s and 16GB of RAM on our test system, 32GB on
production. After going live with the system last week, users started
complaining almost immediately about slow performance. Upon investigation,
it was determined that we were thrashing swap pretty heavily. I do not
mean data just sitting in swap, vmstat reported constant si and so
numbers, sometimes over a thousand in a 5 second sample period. We could
tell from the output of the free command and top that there was a large
amount of RAM dedicated to disk caching, so we decided to decrease the
disk cache. I set the vm.pagecache parameter on the test platform to ?1 5
10? and it had absolutely no effect at all that I could see. The
developers were able to easily generate disk cache that filled over 90% of
RAM. I thought that pagecache setting limited cache to 10% of RAM?
We also tried setting the hugetlb_pool parameters to dedicate 8GB of huge
pages for the SGA. I set this with the command ?sysctl ?w
vm.hugetlb_pool=8192? and according to /proc/meminfo I got 8 pages of
2048K pages. That did not make sense to me, so I put the same setting in
sysctl.conf and rebooted. The server hung at boot as it was ?Setting
kernel parameters.? I simply commented out the hugetlb_pool setting at it
booted without error. Can anyone tell me what I?m missing here or
recommend some better setting for our environment?
Red Hat Enterprise Linux AS release 3 (Taroon Update 7)
Linux XXX.XXXX.com 2.4.21-40.ELsmp #1 SMP Thu Feb 2 22:13:55 EST 2006
x86_64 x86_64 x86_64 GNU/Linux
# free
total used free shared buffers cached
Mem: 16010356 13834384 2175972 0 287552 12683848
-/+ buffers/cache: 862984 15147372
Swap: 8388472 0 8388472
# cat /proc/sys/vm/pagecache
1 5 10
# cat /proc/cpuinfo
processor : 0
vendor_id : AuthenticAMD
cpu family : 15
model : 33
model name : AMD Opteron (tm) Processor 880
physical id : 0
siblings : 2
core id : 0
cpu cores : 2
stepping : 2
cpu MHz : 2396.886
cache size : 1024 KB
fpu : yes
fpu_exception : yes
cpuid level : 1
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca
cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext lm 3dnowext
3dnow
bogomips : 4771.02
TLB size : 1088 4K pages
clflush size : 64
address sizes : 40 bits physical, 48 bits virtual
power management: ts fid vid ttp
(?. duplicated 7 more times)
Jim Williams
Linux Administrator
Desk: (407) 804-8185
Cell: (407) 687-4532
Jim.Williams@(protected)
Taroon-list mailing list
Taroon-list@(protected)
https://www.redhat.com/mailman/listinfo/taroon-list

 Have you enabled direct I/O or AIO for
Oracle and Linux? 
 http://www.rampant-books.com/t_oracle_direct
_i_o.htm
 
 We run the same exact Oracle/Linux/Hardware
configuration here and don't have that issue. You may also make use of
the sync or update commands like people do on Unix systems.
 What does `cat /proc/meminfo` show?
 
 -David Knight
 
 
 
 
 
<table width=100%>
<tr valign=top>
<td width=40%>"Jim Williams"
<Jim.Williams@(protected)> 
 Sent by: taroon-list-bounces@(protected)
06/09/2006 02:58 PM
<table border>
<tr valign=top>
<td bgcolor=white>
<div align=center>Please respond to 
"Discussion of Red Hat Enterprise Linux 3 (Taroon)" <taroon-list
@(protected)></div></table>
 
<td width=59%>
<table width=100%>
<tr valign=top>
<td>
<div align=right>To</div>
<td>taroon-list@(protected)
<tr valign=top>
<td>
<div align=right>cc</div>
<td>
<tr valign=top>
<td>
<div align=right>Subject</div>
<td>pagecache and hugetlb tuning for Oracle
DB operations</table>
 
<table>
<tr valign=top>
<td>
<td></table>
 </table>
 
 
 I am managing a new server configuration
to support Oracle 9i
v 9.2.0. The SGA
is approximately 7 GB and we are running on a pair
of new HP DL585?s
with 4 dual-core Opteron CPU?s and 16GB
of RAM on our test system, 32GB on production. After
going live with the system last week, users started complaining
almost immediately
about slow performance. Upon investigation,
it was determined that we were thrashing swap pretty heavily. I do not
mean data just sitting
in swap, vmstat reported constant si and so numbers, sometimes
over a thousand in a 5 second sample

period. We could tell from the output
of the free command and top that there was a large amount of RAM dedicated
to disk caching, so we decided to decrease the disk cache. I set the vm
.pagecache
parameter on the
test platform to

?1 5 10? and it had absolutely no effect
at all that I could see. The developers were able to easily generate disk
cache that filled over 90% of RAM.  I
thought that pagecache setting limited cache to 10% of RAM?
We also tried setting the hugetlb_pool

parameters to dedicate 8GB of huge pages
for the SGA. I set
this with the command 
?sysctl
?w vm.hugetlb_pool=8192? and according
to /proc/meminfo I got 8 pages of 2048K pages. That did not make sense
to me, so I put the same setting in sysctl.conf and rebooted. The server
hung at boot as it was 
?Setting
kernel parameters.? I simply commented out the hugetlb_pool setting at
it booted without error. Can anyone tell me what I?m missing here or recommend
some better setting for our environment?
Red Hat Enterprise Linux AS release 3 (Taroon
Update 7)
Linux XXX.XXXX.com
2.4.21-40.ELsmp #1 SMP Thu Feb 2 22:13:55 EST 2006 x86_64 x86_64 x86_64
GNU/Linux
# free
           
 total       used       free  
  shared    buffers     cached
Mem:      16010356  
13834384    2175972          0  
  287552   12683848
-/+ buffers/cache:     862984  
15147372
Swap:      8388472  
       0    8388472
# cat /proc/sys/vm/pagecache
1       5      
10
# cat /proc/cpuinfo
processor       : 0
vendor_id       : AuthenticAMD
cpu family      : 15
model          
: 33
model name      : AMD Opteron
(tm) Processor 880
physical id     : 0
siblings        : 2
core id         : 0
cpu cores       : 2
stepping        : 2
cpu MHz         : 2396.886
cache size      : 1024 KB
fpu            
: yes
fpu_exception   : yes
cpuid level     : 1
wp            
 : yes
flags          
: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36
clflush mmx fxsr sse sse2 ht syscall nx mmxext lm 3dnowext 3dnow
bogomips        : 4771.02
TLB size        : 1088
4K pages
clflush size    : 64
address sizes   : 40 bits physical,
48 bits virtual
power management: ts fid vid ttp
(?. duplicated 7 more times)
Jim Williams
Linux Administrator
Desk: (407) 804-8185
Cell: (407) 687-4532
<a href=mailto:Jim.Williams@(protected)>Jim.Williams@(protected)</a><tt>--
 
Taroon-list mailing list 
Taroon-list@(protected) 
https://www.redhat.com/mailman/listinfo/taroon-list</tt>


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