Messages in this thread |  | | | Date | Thu, 12 Feb 2009 13:57:24 +0800 | | From | Miao Xie <> | | Subject | Re: [PATCH] cpuset: fix allocating page cache/slab object on the unallowed node when memory spread is set |
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on 2009-2-12 9:19 Paul Menage wrote: > On Wed, Feb 11, 2009 at 4:54 PM, Nick Piggin <nickpiggin@yahoo.com.au> wrote: >> It would be possible, depending on timing, for the allocating thread to >> see either pre or post mems_allowed even if access was fully locked. > > Right - seeing either the pre set or the post set is fine. > >> The only difference is that a partially changed mems_allowed could be >> seen. But what does this really mean? Some combination of the new and >> the old nodes. I don't think this is too much of a problem. > > But if the old and new nodes are disjoint, that could lead to seeing no nodes. > > Also, having the results of cpuset_zone_allowed() and > cpuset_current_mems_allowed change at random times over the course of > a call to alloc_pages() might cause interesting effects (e.g. we make > progress freeing pages from one set of nodes, and then call > get_page_from_freelist() on a different set of nodes). > >> This could work if we *really* need an atomic snapshot of mems_allowed. >> seqcount synchronisation would be an alternative too that could allow >> sleeping more easily than SRCU (OTOH if you don't need sleeping, then >> RCU should be faster than seqcount). >> >> But I'm not convinced we do need this to be atomic. > > It's possible that I'm being overly-paranoid here. The decision to > make mems_allowed updates be purely pulled by the task itself predates > my involvement with cpusets code by a long time. Paul Jackson (CC'd) > may have opinions here, but I suspect his sgi.com email address no > longer works, and I don't have any more recent address for him.
I think it's pj@usa.net(CC'd).
Author: Paul Jackson <pj@sgi.com> Date: Fri Oct 3 15:23:42 2008 -0700
cpusets: remove pj from cpuset maintainers
Remove myself from the kernel MAINTAINERS file for cpusets. I am leaving SGI and probably will not be active in Linux kernel work. I can be reached at <pj@usa.net>. Contact Derek Fults <dfults@sgi.com> for future SGI+cpuset related issues. I'm off to the next chapter of this good life.
Signed-off-by: Paul Jackson <pj@sgi.com> Cc: Paul Menage <menage@google.com> Cc: Derek Fults <dfults@sgi.com> Cc: John Hesterberg <jh@sgi.com> Cc: Paul Jackson <pj@usa.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Thanks! Miao
> > Paul > > >
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