Date: Sun, 23 May 2004 10:32:47 -0700 From: JG <amd64list@jpgsworld.com> To: freebsd-threads@freebsd.org Subject: Re: Why is MySQL nearly twice as fast on Linux? Message-ID: <5.2.0.9.2.20040523102747.015557e8@mail.ojoink.com> In-Reply-To: <40B0DADE.1070605@he.iki.fi> References: <5.2.0.9.2.20040523090659.01628af8@mail.ojoink.com> <5.2.0.9.2.20040522135338.0158cc50@mail.ojoink.com> <5.2.0.9.2.20040522100318.01598f50@mail.ojoink.com> <5.2.0.9.2.20040522052606.0156fd70@mail.ojoink.com> <5.2.0.9.2.20040521154458.01627688@127.0.0.1> <5.2.0.9.2.20040521154458.01627688@127.0.0.1> <5.2.0.9.2.20040522052606.0156fd70@mail.ojoink.com> <5.2.0.9.2.20040522100318.01598f50@mail.ojoink.com> <5.2.0.9.2.20040522135338.0158cc50@mail.ojoink.com> <5.2.0.9.2.20040523090659.01628af8@mail.ojoink.com>
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At 08:09 PM 5/23/2004 +0300, you wrote: >JG wrote: > >> >> >> >>I am just a layman here, but what does this mean? >You seem to have a very small number of active threads. When I tried=20 >supersmack on fairly old machine (800MHz dual pentium) I get ~30 active=20 >mysql threads using CPU between 1.5% and 3.5%. You mean where I have the 3 instances of mysqld running in top? You have=20 ~30 instances? Why would your box use more? Is there any configuration or flag in mysql=20 that would cause this? How was your mysql compiled? What version of FreeBSD are you running? >I would suspect the test is limited by context switch and syscall=20 >overhead. With the old machine I see >70000 syscalls and >20000 context=20 >switches a second. So I suspect FreeBSD syscall overhead compared to linux= =20 >must be higher. Mysql also asks for time repeatedly so make sure you are=20 >running ACPI timecounters. (don=B4t know if they are available on AMD64). I know that this FreeBSD/AMD64 reports that it is using ACPI... how do I=20 find out if its using timecounters, or using them properly? FWIW... amd64f# cat /var/log/dmesg.today | grep ACPI ACPI APIC Table: <A M I OEMAPIC > Timecounter "ACPI-fast" frequency 3579545 Hz quality 1000 cpu0: <ACPI CPU> on acpi0 pcib0: <ACPI Host-PCI bridge> port 0xcf8-0xcff on acpi0 pci0: <ACPI PCI bus> on pcib0 pcib1: <ACPI PCI-PCI bridge> at device 6.0 on pci0 pci3: <ACPI PCI bus> on pcib1 pcib2: <ACPI PCI-PCI bridge> at device 10.0 on pci0 pci2: <ACPI PCI bus> on pcib2 pcib3: <ACPI PCI-PCI bridge> at device 11.0 on pci0 pci1: <ACPI PCI bus> on pcib3
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