Ashley M. Kirchner wrote:
Hi folks.
I'm posting this to both the Fedora as well as the CentOS lists in
hopes that somewhere, someone can help me figure out what's going on. I
have a dual Xeon 3GHz server that's performing rather slow when it comes
to disk activities.
The machine is configured with a single 160 GiB OS drive (with CentOS
5.0) and 4x500 GiB drives setup in a RAID-5 configuration. All drives
are setup for 3.0 GiB SATA link, and the motherboard also supports
that. Looking in dmesg when the system comes up, I see that reflected
as well:
ata1: SATA link up 3.0 Gbps (SStatus 123 SControl 300)
ata1.00: ATA-7, max UDMA/133, 312581808 sectors: LBA48 NCQ (depth 0/32)
ata1.00: configured for UDMA/133
scsi1 : ahci
ata2: SATA link up 3.0 Gbps (SStatus 123 SControl 300)
ata2.00: ATA-7, max UDMA/133, 976773168 sectors: LBA48 NCQ (depth 0/32)
ata2.00: configured for UDMA/133
scsi2 : ahci
ata3: SATA link up 3.0 Gbps (SStatus 123 SControl 300)
ata3.00: ATA-7, max UDMA/133, 976773168 sectors: LBA48 NCQ (depth 0/32)
ata3.00: configured for UDMA/133
scsi3 : ahci
ata4: SATA link up 3.0 Gbps (SStatus 123 SControl 300)
ata4.00: ATA-7, max UDMA/133, 976773168 sectors: LBA48 NCQ (depth 0/32)
ata4.00: configured for UDMA/133
scsi4 : ahci
ata5: SATA link up 3.0 Gbps (SStatus 123 SControl 300)
ata5.00: ATA-7, max UDMA/133, 976773168 sectors: LBA48 NCQ (depth 0/32)
ata5.00: configured for UDMA/133
scsi5 : ahci
Now, I don't know what performance numbers *should* be, but on a 1.8
GiB copy on the RAID (cp from one location to another on the RAID), it
gets done in just under 50 seconds. If I try to delete the folder
afterwards (rm -rf FOLDER) it takes a few seconds to do so, however if I
delete the CONTENTS of the folder, it does so within a fraction of a
second (but then 'sync' takes a few seconds to catch up.)
That same folder that I'm copying contains 452 jpeg files in it,
ranging from 2.5 to 6.2 MiB. Doing some image processing on them is
where it takes a long time. At the moment I'm doing a simple thumbnail
creation with the ImageMagick suite (convert FILE -thumbnail "200x200>'
`basename FILE .jpg`.th.jpg) and it takes upwards of 8 minutes to
complete. The whole time it's running, 'top' reports the server load as
follows: load average: 1.06, 1.00, 0.81 And the CPU usage is around 9%.
Interestingly, if I run the same command and have it create .png
instead, it takes longer, but I won't go there just yet. My question
is, is this the expected performance on something like this, or should I
be able to get better results? Is there something I should or could do
to speed up disk based processes?
Or is this something where it's more memory intensive and I need to
look at adding more (right now it has 2 GiB of memory.)
This problem is causing one of our web sites to time out because it's
trying to process hundreds of image files and generate thumbnails, and
it's taking forever to do that. So I'm starting at the bottom of the
pile here, hardware. If it turns out the hardware is fine, and there's
nothing else that can be done to speed it up, then I'll move forward to
other possible culprits, such as the routines within the site scripts
themselves...
At first I would suggest against cross-posting. The two OSes are not
exactly the same. Also you should specify your exact OS.
Regarding the 2 CPUs, do you have the service irqbalance running? Also
if not running CentOS 5.0, have you installed the SMP kernel?
Regarding parallel processing, I do not know much about GNU/Linux
parallelization, however I assume a given script is running on one CPU
of the two.
Obviously there are others here with more insight about this than me.
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