Ubuntu Performance Question

[lada-h8kxHjy+vg4AvxtiuMwx3w at public.gmane.org]

> You can also check DMA on the drive using
>
> hdparm -d /dev/hda (substitute you drive as appropriate, doesn't apply
> to SCSI/SATA/USB drives)

There are two SCSI drives in the P4 box. Here are timing results: 

lsvatos at grinder:~$ sudo hdparm -t /dev/sda

/dev/sda:
 Timing buffered disk reads:  120 MB in  3.08 seconds =  38.96 MB/sec
lsvatos at grinder:~$ sudo hdparm -T /dev/sda

/dev/sda:
 Timing cached reads:   2760 MB in  2.00 seconds = 1379.91 MB/sec

>
> On 7/10/07, Lennart Sorensen <lsorense at csclub.uwaterloo.ca> wrote:
> > On Tue, Jul 10, 2007 at 03:36:25PM -0400, lada at agawa.com wrote:
> > > I migrated my Subversion server from a 800Mhz Pentium 3 with 512 MB of
> > > memory to a 3GHz Pentium 4 with 2 GB of memory. They both run Ubuntu
6.06
> > > LTS Linux (2.6.15-26-386 kernel).
> > > The P4 machine seems to be rather slow. Here is truncated output from
top:
> > >
> > > top - 15:19:19 up 5 days, 22:43,  1 user,  load average: 0.33, 0.09,
0.03
> > > Tasks:  56 total,   1 running,  55 sleeping,   0 stopped,   0 zombie
> > > Cpu(s):  4.2% us,  0.0% sy,  0.0% ni, 95.8% id,  0.0% wa,  0.0% hi, 
0.0% si
> > > Mem:   2067576k total,  1474208k used,   593368k free,   213872k
buffers
> > > Swap:  1951800k total,    18904k used,  1932896k free,  1167500k
cached
> > >
> > >   PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
> > >
> > > 15543 lsvatos   17   0  2196 1088  856 R  3.8  0.1   0:00.53 top
> > >
> > > And here from the P3 box:
> > >
> > > top - 15:17:07 up 19 days,  5:09,  1 user,  load average: 0.00, 0.00,
0.00
> > > Tasks:  51 total,   1 running,  50 sleeping,   0 stopped,   0 zombie
> > > Cpu(s):  0.0% us,  0.3% sy,  0.0% ni, 99.7% id,  0.0% wa,  0.0% hi, 
0.0% si
> > > Mem:    515284k total,   418848k used,    96436k free,    72740k
buffers
> > > Swap:   979832k total,    18904k used,   960928k free,   262132k
cached
> > >
> > >   PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
> > >
> > >  9848 lsvatos   16   0  2192 1076  856 R  0.3  0.2   0:00.16 top
> > >
> > > How is it possible for the same program to consume 10 times the CPU
time?
> > > I would appreciate any suggestions.
> >
> > Not having DMA enabled for disk access can cause quite a severe cpu hit.
> >
> > What does dmesg say on both?
> >
> > --
> > Len Sorensen
> > --


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