dbzinit error ...

Ian Freislich iang at uunet.co.za
Thu Nov 4 12:18:00 UTC 1999


> The Hermit Hacker wrote:
> 
> > Ummmm...all and well, but this is a FreeBSD 3.3-STABLE machine I've been
> > hit with this on, or is this an INN flag?
> 
> Didn't know FreeBSD supported mmap()ing large files.  Coulda saved me a
> heap of typing when installing the last news server. :-)
> 
> Do you have more information regarding this, like what defines exactly to
> use?  `man -k large' doesn't show up anything related to it...

I would think it very surprising if the INN code mmaps the entire
buffer, since a sequential scan of an entire buffer would cause
the whole buffer to be paged into memory, which in turn cause just
about everything else to be paged out. Only dirty pages within the
buffer - those pages wich have been modified in memory - would be
paged out to swap as they get displaced by more data being paged
in.

If you need to read an article, I would expect MMAP to be called
with offset = the byte offset into the buffer for where the article
is located, and len = the size of the article.

If articles are being written into the buffer, the same applies,
except that the area of the file currently MMAPed could be larger,
say 16MB or so and data written until the end of that portion is
reached, then MUNMAPed and the next part of the file MMAPed

I see no vaild requirement for any large region of a file to be
MMAPed, unless of course I've missed something or raw partitions
are handled differently.

I suspect that most of the limit folks experience is from file
system limitations on large files. I don't think that anybody has
an 8TB cycbuf yet :)



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