K 10
svn:author
V 7
glebius
K 8
svn:date
V 27
2017-10-09T21:06:16.441955Z
K 7
svn:log
V 647
Improvements to sendfile(2) mbuf free routine.

o Fall back to default m_ext free mech, using function pointer in
  m_ext_free, and remove sf_ext_free() called directly from mbuf code.
  Testing on modern CPUs showed no regression.
o Provide internally used flag EXT_FLAG_SYNC, to mark that I/O uses
  SF_SYNC flag.  Lack of the flag allows us not to dereference
  ext_arg2, saving from a cache line miss.
o Create function sendfile_free_page() that later will be used, for
  multi-page mbufs.  For now compiler will inline it into
  sendfile_free_mext().

In collaboration with:	gallatin
Differential Revision:	https://reviews.freebsd.org/D12615

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