Thread: Slow Performance with 7.4.1
Hi, I just installed pg 7.4.1 on a new system P4, 3.2Gh HT, 1GB Mem, RH9 and discovered that some of the processes have become extremely slow. Mainly I am talking about a SELECT COUNT(*) or VACUUM. Before running the same database on a P4. 2Ghz 412MB mem, I got the job done in some cases half the time. The weird thing however is, that normal inserts seem to be much faster on the new system and I am wondering if it is Postgres or HW related. Does anyone has an advise ? Thanks Alex
Alex <alex@meerkatsoft.com> writes: > Hi, > I just installed pg 7.4.1 on a new system P4, 3.2Gh HT, 1GB Mem, RH9 > and discovered that some of the processes have become extremely > slow. Mainly I am talking about a SELECT COUNT(*) or VACUUM. > > Before running the same database on a P4. 2Ghz 412MB mem, I got the > job done in some cases half the time. > > The weird thing however is, that normal inserts seem to be much faster > on the new system and I am wondering if it is Postgres or HW related. > > Does anyone has an advise ? What kind of disk hardware is on the two systems? -Doug
The old system has a 80GB, 5200rpm ATA , the new system a 120GB, 7200rpm ATA. The new system should at least not be slower. Also, on the new system I have a separate partition for the database. If I run a Vacuum or a SELECT COUNT(*) on a larger table (2-6 million records) the systems responds very slow, the screen almost freezes. Thanks Alex Doug McNaught wrote: >Alex <alex@meerkatsoft.com> writes: > > > >>Hi, >>I just installed pg 7.4.1 on a new system P4, 3.2Gh HT, 1GB Mem, RH9 >>and discovered that some of the processes have become extremely >>slow. Mainly I am talking about a SELECT COUNT(*) or VACUUM. >> >>Before running the same database on a P4. 2Ghz 412MB mem, I got the >>job done in some cases half the time. >> >>The weird thing however is, that normal inserts seem to be much faster >>on the new system and I am wondering if it is Postgres or HW related. >> >>Does anyone has an advise ? >> >> > >What kind of disk hardware is on the two systems? > >-Doug > >---------------------------(end of broadcast)--------------------------- >TIP 7: don't forget to increase your free space map settings > > > >
Alex <alex@meerkatsoft.com> writes: > The old system has a 80GB, 5200rpm ATA , the new system a 120GB, > 7200rpm ATA. The new system should at least not be slower. Also, on > the new system I have a separate partition for the database. > > If I run a Vacuum or a SELECT COUNT(*) on a larger table (2-6 million > records) the systems responds very slow, the screen almost freezes. Sounds like you may not have DMA enabled on the newer machine, or there is some other kernel problem that slows the disk down. You might try running Bonnie or a similar disk benchmark to make sure you are getting the right disk performance. -Doug
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Yup, DMA is not enabled, probably that is the problem. Tried to enable it but get an error HDIO_SET_DMA failed: Operation not permitted. Thanks for the hint. Alex Doug McNaught wrote: >Alex <alex@meerkatsoft.com> writes: > > > >>The old system has a 80GB, 5200rpm ATA , the new system a 120GB, >>7200rpm ATA. The new system should at least not be slower. Also, on >>the new system I have a separate partition for the database. >> >>If I run a Vacuum or a SELECT COUNT(*) on a larger table (2-6 million >>records) the systems responds very slow, the screen almost freezes. >> >> > >Sounds like you may not have DMA enabled on the newer machine, or >there is some other kernel problem that slows the disk down. You >might try running Bonnie or a similar disk benchmark to make sure you >are getting the right disk performance. > >-Doug > > > >
On Tue, Jan 06, 2004 at 12:50:05AM +0900, Alex wrote: > Yup, DMA is not enabled, probably that is the problem. Tried to enable > it but get an error HDIO_SET_DMA failed: Operation not permitted. probably You have no support for Your boards chipset enabled. You can do this ether by loading the proper module or compiling this into Your kernel. Hope this helps. Greetings, -tb -- Thomas Beutin tb@laokoon.IN-Berlin.DE Beam me up, Scotty. There is no intelligent live down in Redmond.
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