From: ebiederm@xmission.com (Eric W. Biederman)
To: colpatch@us.ibm.com
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org, LSE <lse-tech@lists.sourceforge.net>,
Andrew Morton <akpm@zip.com.au>,
Martin Bligh <mjbligh@us.ibm.com>,
Michael Hohnbaum <hohnbaum@us.ibm.com>
Subject: Re: [rfc][patch] Memory Binding API v0.3 2.5.41
Date: 15 Oct 2002 11:21:26 -0600 [thread overview]
Message-ID: <m1y98z39ex.fsf@frodo.biederman.org> (raw)
In-Reply-To: <3DAB5DF2.5000002@us.ibm.com>
Matthew Dobson <colpatch@us.ibm.com> writes:
> Eric W. Biederman wrote:
> > Matthew Dobson <colpatch@us.ibm.com> writes:
> >>Greetings & Salutations,
> >> Here's a wonderful patch that I know you're all dying for... Memory
> >>Binding! It works just like CPU Affinity (binding) except that it binds a
> >>processes memory allocations (just buddy allocator for now) to specific memory
>
> >>blocks.
> > Due we want this per numa area or simply per zone? My suspicion is that
> > internally at least we want this per zone.
> I think that per memory block is better.
[snip]
> I'm not fanatically
> opposed to per zone binding, though, and if there is a general agreement that it
> would be better that way, I don't think it would be unreasonably difficult to
> change it.
My only feeling with zones is that it could be useful in the non numa cases,
if it was per zone.
But unless this API becomes is a pure hint we need at least one specifier that
says writing to swap is o.k.
> > The API doesn't make much sense at the moment.
> Hmm.. That is unfortunate, I'd aimed to make it as simple as possible.
Simple is good only if the proper pieces are connected.
> > 1) You are operating on tasks and not mm's, or preferably vmas.
> Correct. There are plans (somewhere inside my cranium) to allow binding at that
>
> granularity. For now, per task seemed an appropriate level.
It makes it terribly unpredictable. If you have two threads each bound
to a different location there are race conditions which area the memory
is allocated from.
> > 2) sys_mem_setbinding does not move the mm to the new binding.
> Also correct. A task may wish to allocate several large data structures from
> one memory area, rebind, do more allocations, rebind, ad nauseum. There are
> plans to have a flag that, if set, would force relocation of all currently
> allocated memory.
Actually the bindings need to stick to the vma or to the struct address_space.
Otherwise you are talking about an allocation hint, as swapping can trivially
undue it and nothing happens when the actual call is made. A hint is a very
different thing from a binding.
And if we stick this to struct address_space for the non anonymous cases
having a fmem_setbinding(struct fd) that works on files would be a useful
thing as well.
> > 5) mprotect is the more natural model rather than set_cpu_affinity.
> Well, I think that may be true for the API you are imagining (per zone, per
> mm/vma, etc), not the one that I've written.
For a binding with respect to memory I imagine things like mlock(). For
anything else you are talking a future hint to the memory allocators, which
feels less much useful.
Eric
prev parent reply other threads:[~2002-10-15 17:17 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-10-10 1:12 [rfc][patch] Memory Binding API v0.3 2.5.41 Matthew Dobson
2002-10-10 3:05 ` Andrew Morton
2002-10-10 18:29 ` Matthew Dobson
2002-10-10 4:06 ` Martin J. Bligh
2002-10-10 18:43 ` Matthew Dobson
2002-10-10 9:00 ` Arjan van de Ven
2002-10-10 18:55 ` Matthew Dobson
2002-10-10 10:06 ` Arjan van de Ven
2002-10-10 11:22 ` Alan Cox
2002-10-10 11:28 ` William Lee Irwin III
2002-10-10 19:09 ` Matthew Dobson
2002-10-10 19:06 ` Matthew Dobson
2002-10-10 19:01 ` Matthew Dobson
2002-10-13 22:22 ` Eric W. Biederman
2002-10-15 0:14 ` Matthew Dobson
2002-10-15 0:20 ` Martin J. Bligh
2002-10-15 0:38 ` Matthew Dobson
2002-10-15 0:43 ` Martin J. Bligh
2002-10-15 0:51 ` Matthew Dobson
2002-10-15 0:58 ` William Lee Irwin III
2002-10-15 0:55 ` [Lse-tech] " john stultz
2002-10-15 1:08 ` Martin J. Bligh
2002-10-15 1:20 ` William Lee Irwin III
2002-10-15 1:29 ` Martin J. Bligh
2002-10-15 1:40 ` William Lee Irwin III
2002-10-15 1:57 ` William Lee Irwin III
2002-10-15 1:08 ` William Lee Irwin III
2002-10-15 1:16 ` Martin J. Bligh
2002-10-15 17:21 ` Eric W. Biederman [this message]
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