[CentOS] Too much cpu wait on nfs server when we need to read data on it

Hi,

You can find below the spec of my server:

cat /proc/cpuinfo 
processor	: 0
vendor_id	: AuthenticAMD
cpu family	: 15
model		: 37
model name	: AMD Opteron(tm) Processor 248
stepping	: 1
cpu MHz		: 2200.034
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 syscall nx mmxext fxsr_opt lm 3dnowext 3dnow pni lahf_lm
bogomips	: 4400.06
TLB size	: 1024 4K pages
clflush size	: 64
cache_alignment	: 64
address sizes	: 40 bits physical, 48 bits virtual
power management: ts fid vid ttp

processor	: 1
vendor_id	: AuthenticAMD
cpu family	: 15
model		: 37
model name	: AMD Opteron(tm) Processor 248
stepping	: 1
cpu MHz		: 2200.034
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 syscall nx mmxext fxsr_opt lm 3dnowext 3dnow pni lahf_lm
bogomips	: 4399.42
TLB size	: 1024 4K pages
clflush size	: 64
cache_alignment	: 64
address sizes	: 40 bits physical, 48 bits virtual
power management: ts fid vid ttp

free
             total       used       free     shared    buffers     cached
Mem:       2059236    2049896       9340          0       9800    1874828
-/+ buffers/cache:     165268    1893968
Swap:      4095992        112    4095880


Linux 1-NFS.domain.com 2.6.18-164.9.1.el5 #1 SMP Tue Dec 15 20:57:57 EST 2009 x86_64 x86_64 x86_64 GNU/Linux

  --- Physical volume ---
  PV Name               /dev/sdc1
  VG Name               vgspace
  PV Size               4.55 TB / not usable 1.97 MB
  Allocatable           yes 
  PE Size (KByte)       4096
  Total PE              1192067
  Free PE               795267
  Allocated PE          396800
   
  --- Physical volume ---
  PV Name               /dev/sdd1
  VG Name               vgspace
  PV Size               4.55 TB / not usable 1.97 MB
  Allocatable           yes 
  PE Size (KByte)       4096
  Total PE              1192067
  Free PE               808067
  Allocated PE          384000

I need  ext4 for file bigger than 2TB.

/dev/mapper/vgspace-vol1 on /vol/vol1 type ext4 (rw,noatime)
/dev/mapper/vgspace-vol2 on /vol/vol2 type ext4 (rw,noatime)

# tune2fs -l /dev/mapper/vgspace-vol1
tune2fs 1.39 (29-May-2006)
tune2fs: Filesystem has unsupported feature(s) while trying to open /dev/mapper/vgspace-vol1
Couldn't find valid filesystem superblock.
# tune2fs -l /dev/mapper/vgspace-vol2
tune2fs 1.39 (29-May-2006)
tune2fs: Filesystem has unsupported feature(s) while trying to open /dev/mapper/vgspace-vol2
Couldn't find valid filesystem superblock.

export nfs : 

/vol/vol1 192.168.*.0/255.255.255.0(async,no_subtree_check,rw,no_root_squash)
/vol/vol2 192.168.*.0/255.255.255.0(async,no_subtree_check,rw,no_root_squash)

Best regards

Fabien FAYE






----- Original Message -----
From: "Jim Perrin" <jperrin at gmail.com>
To: "CentOS mailing list" <centos at centos.org>
Sent: Monday, January 25, 2010 2:27:41 PM
Subject: Re: [CentOS] Too much cpu wait on nfs server when we need to read	data on it

On Mon, Jan 25, 2010 at 8:39 AM, fabien faye <fabien at faye.eu> wrote:
> Hi,
>
> I have a big server with 24 Disk on 2 3ware card.

Define 'big'. You're not giving much in terms of memory or cpu specs.

> When i write data on my nfs server everything is fine but when i want to read data i have a lot of cpu wait.

Okay. Have you looked at any performance tuning or elevator/scheduler
adjustments? File system tuning? What have you tried on your own so
far to debug this?

> about the file system, i use ext4 on LVM partition.

Why? Is there a performance reason for you to use ext4 vs ext3?

> Do you have any idea about that.

Not based on the little information you've provided. It would help for
you to supply more detail, and the things you've already looked at.

-- 
During times of universal deceit, telling the truth becomes a revolutionary act.
George Orwell
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