Re: [PATCH/RFC 0/8] Mapped File Policy Overview

[Lee Schermerhorn <Lee.Schermerhorn@hp.com>]

On Fri, 2007-05-25 at 08:25 -0700, Christoph Lameter wrote:
> On Fri, 25 May 2007, Lee Schermerhorn wrote:
> 
> > It's easy to fix.  The shared policy support is already there.  We just
> > need to generalize it for regular files.  In the process,
> > *page_cache_alloc() obeys "file policy", which will allow additional
> > features such as you mentioned:  global page cache policy as the default
> > "file policy".
> 
> A page cache policy would not need to be file based. It would be enough 
> to have a global one or one per cpuset. And it would not suffer from the 
> vanishing act of the inodes.

True, but shared, mmap'ed file policy does need to be file based, and
that is my objective.  I merely point out that we can easily add the
page cache policy as the fall back when a file has no explicit policy.

> 
> > By the way, I think we need the numa_maps fixes in any case because the
> > current implementation lies about shmem segments if you look at any task
> > that didn't install [all of] the policy on the segment, unless it
> > happens to be a child of the task that did install the policy and that
> > child was forked after the mbind() calls.  I really dislike all of those
> > "ifs" and "unlesses"--I found it humorous in the George Carlin routine,
> > but not in user/programming interface design.
> 
> Could you separate out a patch that fixes these issues?

Could do, but does that improve the chances for acceptance of this patch
set?  If the patch set is accepted, with whatever corrections might be
required, we get the numa_maps fix.  So, I'm not currently motivated to
post a separate patch.

Lee

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