[CentOS] Slow performance
Ioannis Vranos
ivranos at freemail.gr
Mon Apr 30 18:13:59 UTC 2007
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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