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> yamt%mwd.biglobe.ne.jp@localhost (YAMAMOTO Takashi) wrote:
>> what's the status of emap and pipe?
> If I remember correctly, I could not get real performance improvement
> of pipe with UVM emap. Higher chances are that it would improve socket
> performance. Also, pipe has direct I/O disabled (PIPE_NODIRECT) due
> to some rare lock-ups when switching between direct/buffered. AFAIK,
> we have this bug since netbsd-3 times or even earlier.
can you provide a recipe to reproduce the lock-up?
> However, I tend to question whether UVM emap was a right approach to
> the problem. For amd64, we should definitely have a direct mapping
> of kernel space (I was planning to revive the patch written by chs@,
> but ran out of time) and encourage our users to use amd64 instead
> of i386. Most other architectures have a segment for direct mapping.
> I wonder if we could help i386 with large pages for kernel space..
the real problem for i386 is kva shortage.
direct-mapping only limited part of physical memory would work, tho.
(call the rest of memory highmem!)
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