sendfilev vs writev

Poul-Henning Kamp phk at
Wed Mar 4 23:26:22 CET 2009

The subject of sendfile is compounded by the lack of usable
implementations, but the experience data I have gathered so far is
that you need to have significant paging activity to backing store,
and you still should not enable it for objects smaller than 8-16
VM pages.

sendfile really shines with huge files on vastly overcommitted VM,
such as where it was developed.

For lots of small files, not so much.

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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