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Thread: My VPS Feels slow
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05-11-2008, 07:18 AM #1Junior Guru Wannabe
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My VPS Feels slow
I've got a VPS that I don't currently use for anything.
Every time I jump on and have a think about doing anything it just feels slow. Plenty of free memory and CPU, when I mean not used I really mean it :-)
I've attached a "vmstat 1" from earlier when I installed 4 packages through yum.
It took 2 or 3 minutes just to read through the package list and then another 4 minutes to install the packages. Host is running openvz+hypervm from what I know.
I'm looking for pointers on where I might look to confirm if it is an IO issue or something on the host box I'm on.
Cheers,
J
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05-11-2008, 07:51 AM #2Junior Guru
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Those I/O numbers are very low, when writing a big blank file I see 102544, but this isn't necessarily the problem. It could be that reading through the package list doesn't require that much disc activity.
To get a better understanding you might try these simple tests. To measure CPU speed run
Code:openssl speed bf
Code:openssl speed bf -elapsed
Code:sync ; time (dd if=/dev/zero of=testdiscperf.tmp bs=10M count=10 ; sync)
Hope that helps a little,
JimBlue Room Hosting - High availability UK VPS
KVM Plans - Multiple OS support. Virtual console and CD drive.
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05-11-2008, 08:31 AM #3Junior Guru Wannabe
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Thanks for the ideas Jim.
openssl speed bf
The 'numbers' are in 1000s of bytes per second processed.
type 16 bytes 64 bytes 256 bytes 1024 bytes 8192 bytes
blowfish cbc 86500.40k 87573.68k 89787.65k 93182.07k 93558.82
openssl speed bf -elapsed
The 'numbers' are in 1000s of bytes per second processed.
type 16 bytes 64 bytes 256 bytes 1024 bytes 8192 bytes
blowfish cbc 30927.00k 30707.89k 30544.67k 31774.35k 32350.95k
sync ; time (dd if=/dev/zero of=testdiscperf.tmp bs=10M count=10 ; sync)
/dev/zero didn't exist, created it using:
mknod /dev/zero c 1 5
104857600 bytes (105 MB) copied, 0.457382 seconds, 229 MB/s
real 0m40.436s
user 0m0.000s
sys 0m0.295s
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05-11-2008, 08:45 AM #4Randy
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Doesn't seem slow to me. Are you sure you don't have a network issue? Perhaps the Yum mirror you're using is too far away or overloaded?
What are the results of some traceroutes to popular sites?
Network download speed tests?Fast Serv Networks, LLC | AS29889 | DDOS Protected | Managed Cloud, Streaming, Dedicated Servers, Colo by-the-U
Since 2003 - Ashburn VA + San Diego CA Datacenters
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05-11-2008, 09:36 AM #5Junior Guru
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Ouch, 40 seconds to write 100MB is rather painful. I know this is a terrible test really, you have no way of knowing how much other activity is also sent to disc on the second sync, but even so what you see is what you get. It still takes 40 seconds to write *your* 100MB to disc.
I think this all adds up. If it is an OpenVZ system then it may well be that it is heavily oversubscribed. If the provider is selling more memory than they have then the system will start swapping a lot, hence the poor disc I/O. It doesn't have to be this way, many providers do not oversubscribe so you might want to move if you ever get around to using your VPS.
JimBlue Room Hosting - High availability UK VPS
KVM Plans - Multiple OS support. Virtual console and CD drive.
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05-11-2008, 08:07 PM #6Junior Guru Wannabe
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05-11-2008, 11:15 PM #7Aspiring Evangelist
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Seems like a swapping node to me (according to writing test).
Thank XenSource for Xen.
My personal VPS a full node but on SATA RAID-10 (Xen) I'm getting this
# sync ; time (dd if=/dev/zero of=testdiscperf.tmp bs=10M count=10 ; sync)
10+0 records in
10+0 records out
104857600 bytes (105 MB) copied, 0.325041 seconds, 323 MB/s
real 0m0.786s
user 0m0.000s
sys 0m0.304sLast edited by ctaborda; 05-11-2008 at 11:22 PM.
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05-12-2008, 09:56 AM #8Junior Guru Wannabe
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Nice speeds, I checked against another two XEN VPSs that I have and both take between 4 and 5 seconds for the write, which is close to 20MB/sec, way better than my slow box
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05-13-2008, 07:42 PM #9Junior Guru Wannabe
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Just to update, I was moved to a new node.
Results are much faster now, under 3 seconds to write 100mb to disk as opposed to over a minute in some cases previously.
sync ; time (dd if=/dev/zero of=testdiscperf.tmp bs=10M count=10 ; sync)
10+0 records in
10+0 records out
104857600 bytes (105 MB) copied, 0.201 seconds, 522 MB/s
real 0m2.704s
user 0m0.000s
sys 0m0.237sLast edited by geekboy; 05-13-2008 at 07:43 PM. Reason: Selling
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05-13-2008, 07:50 PM #10Aspiring Evangelist
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Great news!!!
See, it was an oversold machine. Meaning, they were giving more ram than they had, and it was swapping.
Hey great so see they did the right thing for you!
Best of luck!
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05-14-2008, 09:25 AM #11Web Hosting Master
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Last edited by vpsville; 05-14-2008 at 09:30 AM.