Samba + ZFS + sendfile()

[Marcelo Araujo]

Hello Guys,

I'm doing some benchmarks and also implement a new syscal recvfile() for
zero copy. Pretty much similar like sendfile(2). However, using sendfile
with Samba + ZFS has a very bad performance if we compare with Samba +
sendfile() + UFS.

I asked some people and they said it is because the data is cached twice
once in ARC and in a second time on VFS cache.

I got really confused with this approach, and I'm wondering if someone
could give me some explanation how it happens.

Best Regards,
-- 
Marcelo Araujo
araujo at FreeBSD.org