Re: [PERFORM] high load caused by I/O - a hint
On Aug 18, 2004, at 4:18 AM, eleven wrote: Hello, This is not strictly PostgreSQL performance hint, but may be helpful to someone with problems like mine. As I earlier posted, I was experiencing very high load average on one of my Linux database servers (IBM eServer 345, SCSI disks on LSI Logic controller) caused by I/O bottleneck. We have some 335's (I think they are 335s) and until April or so there was a bug in the Fusion MPT driver that would cause it to revert to async narrow mode if hardware RAID was enabled on it. (Performance was horrible - NFS on a 100meg network was 10x faster than local disk!) And on the upside, when I originally researched the problem they hadn't found the bug yet so there were no others around having issues like mine so trying to figure it out was quite difficult. I may see if using that acpi=ht makes any difference as well. -- Jeff Trout <[EMAIL PROTECTED]> http://www.jefftrout.com/ http://www.stuarthamm.net/ ---(end of broadcast)--- TIP 6: Have you searched our list archives? http://archives.postgresql.org
Re: [PERFORM] high load caused by I/O - a hint
eleven wrote: Hello, This is not strictly PostgreSQL performance hint, but may be helpful to someone with problems like mine. As I earlier posted, I was experiencing very high load average on one of my Linux database servers (IBM eServer 345, SCSI disks on LSI Logic controller) caused by I/O bottleneck. INSERTs were really slow, even after many days of tweaking PostgreSQL configuration. The problem appeared to be in the Linux kernel itself - using acpi=ht and noapic boot parameters solved my performance problems. Load average dropped below 1.0 (before, it was as high as ten in peak) and the database works much, much faster. I suggest you to investigate why noapic did the work for you, do you have not well supported device ? At your place also I'd try removing the noapic option and using acpi=noidle Regards Gaetano Mendola ---(end of broadcast)--- TIP 8: explain analyze is your friend
Re: [PERFORM] high load caused by I/O - a hint
...and on Wed, Aug 18, 2004 at 10:18:19AM +0200, eleven used the keyboard: > Hello, > > This is not strictly PostgreSQL performance hint, but may be > helpful to someone with problems like mine. > > As I earlier posted, I was experiencing very high load average > on one of my Linux database servers (IBM eServer 345, SCSI disks on LSI > Logic controller) caused by I/O bottleneck. > > INSERTs were really slow, even after many days of > tweaking PostgreSQL configuration. The problem appeared to be > in the Linux kernel itself - using acpi=ht and noapic boot parameters > solved my performance problems. Load average dropped below 1.0 > (before, it was as high as ten in peak) and the database > works much, much faster. Hello, Did you try with acpi=noidle? This proved to be of help on many an occasion before, and you don't have to give up any functionality over it. It's just that the ACPI BIOS is broken and overloads the system with idle calls. Other than that, general guidelines would be, don't combine APM and ACPI, and rather use proper SMP code for hyperthreaded machines than just the ACPI CPU enumeration feature. There's also a new option with 2.6.8.1, called CONFIG_SCHED_SMT that is supposed to handle some cases SMP code had problems with better, at the cost of slight overhead in other areas. My advice would be, if you have an option to choose between APM and ACPI, go for ACPI. It's the future, it's being developed actively, it does a whole lot more than APM (that was really only about power management), and last but not least, I've been using it for four years on over fifty SMP machines and I never ever had a problem beyond the scope of what noidle could fix (knocks-on-wood). :) HTH, -- Grega Bremec Senior Administrator Noviforum Ltd., Software & Media http://www.noviforum.si/ pgpBeCvzHEtfV.pgp Description: PGP signature
[PERFORM] high load caused by I/O - a hint
Hello, This is not strictly PostgreSQL performance hint, but may be helpful to someone with problems like mine. As I earlier posted, I was experiencing very high load average on one of my Linux database servers (IBM eServer 345, SCSI disks on LSI Logic controller) caused by I/O bottleneck. INSERTs were really slow, even after many days of tweaking PostgreSQL configuration. The problem appeared to be in the Linux kernel itself - using acpi=ht and noapic boot parameters solved my performance problems. Load average dropped below 1.0 (before, it was as high as ten in peak) and the database works much, much faster. -- 11. ---(end of broadcast)--- TIP 7: don't forget to increase your free space map settings
