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Subject: Re: Doing zero-copy stuff in drivers,
 or "is vm_fault_quick_hold_pages() enough" ?
From: "K. Macy" <kmacy@freebsd.org>
To: Adrian Chadd <adrian@freebsd.org>
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>> Right above vm_page_hold():
>> /*
>>  * Keep page from being freed by the page daemon
>>  * much of the same effect as wiring, except much lower
>>  * overhead and should be used only for *very* temporary
>>  * holding ("wiring").
>>  */
>
> What's the definition of "very temporary holding" ? What's the
> behavioural difference?


Long enough to complete a DMA operation versus the lifetime of  an
executing program.