Re: bad lmbench numbers for mmap

V Ganesh (ganesh@vxindia.veritas.com)
Mon, 19 Apr 1999 02:41:38 +0530 (IST)


> From: torvalds@transmeta.com (Linus Torvalds)
[snip]
> Btw, that also explains why we're twice as slow as Solaris: Solaris
> probably does just one copy. Which is not very impressive either, as
> the proprt (2.3.x) way to do it is to do it without a single copy at
> all, and just write it out directly from the page cache page.

not likely. solaris VM is like SVR4, right ?(or rather, the other way
round). their writes go through page cache. their buffer cache is usually
used only for filesystem metadata. so there's no reason to do a copy. but
they have other overheads like having to map the page into kernel space
before doing IO (unlike linux which maps all physical mem, so this step
is trivial).

ganesh

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