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Lines 893-911
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<programlisting>options ADAPTIVE_GIANT # Giant mutex is adaptive.</programlisting> |
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<programlisting>options ADAPTIVE_GIANT # Giant mutex is adaptive.</programlisting> |
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<para>This option causes Giant to be included in the set of mutexes |
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<para>Giant is the name of a mutual exclusion mechanism (a sleep mutex) |
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adaptively spun on.</para> |
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that protects a large set of kernel resources. Today, this is an |
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unacceptable performance bottleneck which is actively being replaced |
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with locks that protect individual resources. The |
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<literal>ADAPTIVE_GIANT</literal> option causes Giant to be included |
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in the set of mutexes adaptively spun on. That is, when a thread |
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wants to lock the Giant mutex, but it is already locked by a thread |
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on another CPU, the first thread will keep running and wait for the |
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lock to be released. Normally, the thread would instead go back to |
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sleep and wait for its next chance to run. If you are not sure, |
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leave this in.</para> |
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<indexterm> |
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<indexterm> |
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<primary>kernel options</primary> |
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<primary>kernel options</primary> |
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<secondary>SMP</secondary> |
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<secondary>SMP</secondary> |
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</indexterm> |
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</indexterm> |
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<programlisting># To make an SMP kernel, the next two are needed |
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<programlisting>device apic # I/O APIC</programlisting> |
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options SMP # Symmetric MultiProcessor Kernel |
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device apic # I/O APIC</programlisting> |
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<para>The above are both required for SMP support, and can also be |
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<para>The apic device enables the use of I/O APIC for interrupt |
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safely enabled on uniprocessor systems.</para> |
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delivery. The apic device can be used in both UP and SMP kernels, but |
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is required for SMP kernels. Add <literal>options SMP</literal> to |
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include support for multiple processors.</para> |
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<programlisting>device isa</programlisting> |
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<programlisting>device isa</programlisting> |
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Lines 1026-1031
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device asr # DPT SmartRAID V, VI and Adaptec SCSI RAID |
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device asr # DPT SmartRAID V, VI and Adaptec SCSI RAID |
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device ciss # Compaq Smart RAID 5* |
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device ciss # Compaq Smart RAID 5* |
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device dpt # DPT Smartcache III, IV - See NOTES for options |
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device dpt # DPT Smartcache III, IV - See NOTES for options |
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device hptmv # Highpoint RocketRAID 182x |
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device iir # Intel Integrated RAID |
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device iir # Intel Integrated RAID |
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device ips # IBM (Adaptec) ServeRAID |
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device ips # IBM (Adaptec) ServeRAID |
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device mly # Mylex AcceleRAID/eXtremeRAID |
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device mly # Mylex AcceleRAID/eXtremeRAID |