Feedback solicited - read performance is awful with PE2650runningRH AS

Anders Berg andersb at eunet.no
Tue Oct 28 16:13:01 CST 2003


FYI,

I am running a PE 2650 2x2.2 Ghz (HT enabled)/ 2 GB RAM / 4x36 GB 15.000 
RPM disks in RAID 1+0 with debian 3.0 but with vanilla kernel + Alan Cox patch.
This is what I get (actually I felt bold and ran it on a prod system that 
was serving webpages at the time. :)):

(root) skatt02:tmp # /usr/bin/time dd if=/dev/zero of=./testfile bs=16384 
count=250000
250000+0 records in
250000+0 records out
0.25user 12.08system 1:38.30elapsed 12%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (118major+17minor)pagefaults 0swaps

(root) skatt02:tmp # /usr/bin/time dd if=./testfile of=/dev/null bs=16384
250000+0 records in
250000+0 records out
0.10user 8.49system 1:04.33elapsed 13%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (118major+21minor)pagefaults 0swaps

Other info:

(root) skatt02:tmp # uname -a
Linux skatt02 2.4.21-rc2-ac2 #1 SMP Thu Oct 9 16:56:34 CEST 2003 i686 unknown

(root) skatt02:tmp # cat /proc/cpuinfo
processor       : 0
vendor_id       : GenuineIntel
cpu family      : 15
model           : 2
model name      : Intel(R) XEON(TM) CPU 2.20GHz
stepping        : 4
cpu MHz         : 2192.995
cache size      : 512 KB
physical id     : 0
siblings        : 1
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 2
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca 
cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm
bogomips        : 4377.80

processor       : 1
vendor_id       : GenuineIntel
cpu family      : 15
model           : 2
model name      : Intel(R) XEON(TM) CPU 2.20GHz
stepping        : 4
cpu MHz         : 2192.995
cache size      : 512 KB
physical id     : 3
siblings        : 1
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 2
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca 
cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm
bogomips        : 4377.80

(root) skatt02:tmp # cat /proc/interrupts
            CPU0       CPU1
   0:   83346636   83351524    IO-APIC-edge  timer
   1:        549        540    IO-APIC-edge  keyboard
   2:          0          0          XT-PIC  cascade
   8:          2          1    IO-APIC-edge  rtc
  14:          4          1    IO-APIC-edge  ide0
  28:   79970164   79811568   IO-APIC-level  eth0
  30:    2419529    2453185   IO-APIC-level  aacraid
NMI:          0          0
LOC:  166708229  166708252
ERR:          0
MIS:          0

(root) skatt02:tmp # w
  23:05:10 up 19 days,  7:02,  3 users,  load average: 0.09, 0.47, 0.53


Anders Berg
Sys.adm
VG Nett // www.vg.no


At 11:12 28.10.2003 +0000, Gary Mansell wrote:
>Hi,
>
>Thanks for your response - I cannot immediately see why your performance
>should be OK when mine is problematic (I have tried this on two
>identical PE2650's) This problem has also been seen on a HP system.
>
>Perhaps you can have a look at the bug #106771 report on
>http://bugzilla.redhat.com as I would be interested to hear if you can
>think of any reason why I am seeing the problem but you are not.
>
>Regards
>
>
>On Tue, 2003-10-21 at 22:07, Wayde Nie wrote:
> > Hi,
> >
> > I've got a PE2650 running RHAS3b2. It has 4-36Gb disks in 2 HW mirror
> > sets (presented as sda and sdb) on a PERC3Di (Adaptec aacraid driver).
> > The box has 2x 2.4GHz Xeon's with HT enabled and 2Gb RAM.
> >
> > The dd test results as follows:
> >
> > [root at feweb tmp]# /usr/bin/time dd if=/dev/zero of=./testfile bs=16384
> > count=250000
> > 250000+0 records in
> > 250000+0 records out
> > 0.29user 47.06system 6:35.95elapsed 11%CPU (0avgtext+0avgdata
> > 0maxresident)k
> > 0inputs+0outputs (138major+15minor)pagefaults 0swaps
> > ~10.34 Mb/s Write rate.
> >
> > [root at feweb tmp]# /usr/bin/time dd if=./testfile of=/dev/null bs=16384
> > 250000+0 records in
> > 250000+0 records out
> > 0.21user 17.91system 3:03.71elapsed 9%CPU (0avgtext+0avgdata
> > 0maxresident)k
> > 0inputs+0outputs (137major+18minor)pagefaults 0swaps
> > [root at feweb tmp]#
> > ~22.26 Mb/s Read rate.
> >
> > > ----------------------------------------------------------------- <
> > > Wayde Nie                                                         <
> > > Software Analyst               Computing and Information Services <
> > > phone: (905)525-9140 ext 23856 McMaster University, CANADA        <
> > > fax:   (905)524-5288           niew at mcmaster.ca                   <
> > > ----------------------[\]--->=\o.:---[\]------------------------- <
> >
> > On Tue, 2003-10-21 at 07:17, Gary Mansell wrote:
> > > I would really appreciate some help from the list here to see if anyone
> > > else is suffering from the same problem that I am. I appear to have
> > > fallen foul of a problem with RH AS products running on Dell PE2650's.
> > >
> > > I have raised bug number #106771 at http://bugzilla.redhat.com and I
> > > have tried to raise the issue with Dell but I am not getting very far -
> > > both parties blame the other and I am stuck in the middle getting
> > > nowhere.
> > >
> > > I have installed RH AS 2.1 and RH AS 3.0b2 and have found that the read
> > > performance from the system mirror is awful - it is less than the write
> > > speed!! If I install RH 9.0 or RH 7.3 the read performance to this same
> > > device is fine.
> > >
> > > Please could anyone who has a Dell PE2650 with a version of RH AS
> > > installed run the following quick and dirty (but representative) disk
> > > performance tests and let me know if they find the same.
> > >
> > > Write Performance:
> > > /usr/bin/time dd if=/dev/zero of=/testfile bs=16384 count=250000
> > >
> > > Read Performance:
> > > /usr/bin/time dd if=/testfile of=/dev/null bs=16384
> > >
> > >
> > > FYI, I have a Dell PE2650 with 2x 2.4GHz Zeons (Hyperthreading enabled),
> > > 2GB RAM, 2x18GB internal system disks in a HW mirror configuration using
> > > the Adaptec PERC 3Di.
>--
>
>Gary Mansell
>Technical Computing Team Leader
>IT Department
>
>Ricardo Consulting Engineers Ltd.
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