Date: Thu, 14 Apr 2011 20:58:44 -0500 From: Alan Cox <alan.l.cox@gmail.com> To: mdf@freebsd.org Cc: FreeBSD Arch <freebsd-arch@freebsd.org> Subject: Re: posix_fallocate(2) Message-ID: <BANLkTineq2=ruCR61pRZ3OBxR_XQX7yHYg@mail.gmail.com> In-Reply-To: <BANLkTimYzJ11w9X1OHShEn2wi6gjHx=YjA@mail.gmail.com> References: <BANLkTimYzJ11w9X1OHShEn2wi6gjHx=YjA@mail.gmail.com>
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On Thu, Apr 14, 2011 at 2:35 PM, <mdf@freebsd.org> wrote: > For work we need a functionality in our filesystem that is pretty much > like posix_fallocate(2), so we're using the name and I've added a > default VOP_ALLOCATE definition that does the right, but dumb, thing. > > The most recent mention of this function in FreeBSD was another thread > lamenting it's failure to exist: > http://lists.freebsd.org/pipermail/freebsd-ports/2010-February/059268.html > > The attached files are the core of the kernel implementation of the > syscall and a default VOP for any filesystem not supporting > VOP_ALLOCATE, which allows the syscall to work as expected but in a > non-performant manner. I didn't see this syscall in NetBSD or > OpenBSD, so I plan to add it to the end of our syscall table. > > What I wanted to check with -arch about was: > > 1) is there still a desire for this syscall? > Page 10 of my paper at http://www.jeffshafer.com/publications/papers/shafer_ispass10.pdf describes how it could improve Hadoop performance (if properly implemented). So, I would encourage you to add it. Alan
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