Re: Way to check whether a particular block is on the shared_buffer?

> -----Original Message-----
> From: pgsql-hackers-owner@postgresql.org
> [mailto:pgsql-hackers-owner@postgresql.org] On Behalf Of Robert Haas
> Sent: Saturday, March 05, 2016 2:42 AM
> To: Kaigai Kouhei(海外 浩平)
> Cc: Jim Nasby; pgsql-hackers@postgresql.org; Amit Langote
> Subject: Re: [HACKERS] Way to check whether a particular block is on the
> shared_buffer?
> 
> On Thu, Mar 3, 2016 at 8:54 PM, Kouhei Kaigai <kaigai@ak.jp.nec.com> wrote:
> > I found one other, but tiny, problem to implement SSD-to-GPU direct
> > data transfer feature under the PostgreSQL storage.
> >
> > Extension cannot know the raw file descriptor opened by smgr.
> >
> > I expect an extension issues an ioctl(2) on the special device file
> > on behalf of the special kernel driver, to control the P2P DMA.
> > This ioctl(2) will pack file descriptor of the DMA source and some
> > various information (like base position, range, destination device
> > pointer, ...).
> >
> > However, the raw file descriptor is wrapped in the fd.c, instead of
> > the File handler, thus, not visible to extension. oops...
> >
> > The attached patch provides a way to obtain raw file descriptor (and
> > relevant flags) of a particular File virtual file descriptor on
> > PostgreSQL. (No need to say, extension has to treat the raw descriptor
> > carefully not to give an adverse effect to the storage manager.)
> >
> > How about this tiny enhancement?
> 
> Why not FileDescriptor(), FileFlags(), FileMode() as separate
> functions like FilePathName()?
>
Here is no deep reason. The attached patch adds three individual
functions.

Thanks,
--
NEC Business Creation Division / PG-Strom Project
KaiGai Kohei <kaigai@ak.jp.nec.com>