Re: Excessive context switching on SMP Xeons
От | Gaetano Mendola |
---|---|
Тема | Re: Excessive context switching on SMP Xeons |
Дата | |
Msg-id | 41630D47.2020704@bigfoot.com обсуждение исходный текст |
Ответ на | Excessive context switching on SMP Xeons (Bill Montgomery <billm@lulu.com>) |
Список | pgsql-performance |
Bill Montgomery wrote: > All, > > I realize the excessive-context-switching-on-xeon issue has been > discussed at length in the past, but I wanted to follow up and verify my > conclusion from those discussions: > > On a 2-way or 4-way Xeon box, there is no way to avoid excessive > (30,000-60,000 per second) context switches when using PostgreSQL 7.4.5 > to query a data set small enough to fit into main memory under a > significant load. > > I am experiencing said symptom on two different dual-Xeon boxes, both > Dells with ServerWorks chipsets, running the latest RH9 and RHEL3 > kernels, respectively. The databases are 90% read, 10% write, and are > small enough to fit entirely into main memory, between pg shared buffers > and kernel buffers. > I don't know if my box is not loaded enough but I have a dual-Xeon box, by DELL with the HT enabled and I'm not experiencing this kind of CS problem, normaly hour CS is around 100000 per second. # cat /proc/version Linux version 2.4.9-e.24smp (bhcompile@porky.devel.redhat.com) (gcc version 2.96 20000731 (Red Hat Linux 7.2 2.96-118.7.2))#1 SMP Tue May 27 16:07:39 EDT 2003 # cat /proc/cpuinfo processor : 0 vendor_id : GenuineIntel cpu family : 15 model : 2 model name : Intel(R) Xeon(TM) CPU 2.80GHz stepping : 7 cpu MHz : 2787.139 cache size : 512 KB fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 2 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2ss ht tm bogomips : 5557.45 processor : 1 vendor_id : GenuineIntel cpu family : 15 model : 2 model name : Intel(R) Xeon(TM) CPU 2.80GHz stepping : 7 cpu MHz : 2787.139 cache size : 512 KB fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 2 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2ss ht tm bogomips : 5570.56 processor : 2 vendor_id : GenuineIntel cpu family : 15 model : 2 model name : Intel(R) Xeon(TM) CPU 2.80GHz stepping : 7 cpu MHz : 2787.139 cache size : 512 KB fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 2 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2ss ht tm bogomips : 5570.56 processor : 3 vendor_id : GenuineIntel cpu family : 15 model : 2 model name : Intel(R) Xeon(TM) CPU 2.80GHz stepping : 7 cpu MHz : 2787.139 cache size : 512 KB fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 2 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2ss ht tm bogomips : 5570.56 Regards Gaetano Mendola
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