Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1525739

Re: [PATCH v3 (re-send)] xen/gntdev: Use mempolicy instead of VM_IO flag to avoid NUMA balancing

Show all headers | View raw

On 11/18/2016 05:27 PM, Hugh Dickins wrote:
> On Fri, 18 Nov 2016, Boris Ostrovsky wrote:
>> On 11/18/2016 04:51 PM, Hugh Dickins wrote:
>>> Hmm, sorry, but this seems overcomplicated to me: ingenious, but an
>>> unusual use of the ->get_policy method, which is a little worrying,
>>> since it has only been used for shmem (+ shm and kernfs) until now.
>>>
>>> Maybe I'm wrong, but wouldn't substituting VM_MIXEDMAP for VM_IO
>>> solve the problem more simply?
>> It would indeed. I didn't want to use it because it has specific meaning
>> ("Can contain "struct page" and pure PFN pages") and that didn't seem
>> like the right flag to describe this vma.
> It is okay if it contains 0 pure PFN pages; and no worse than VM_IO was.
> A comment on why VM_MIXEDMAP is being used there would certainly be good.
> But I do find its use preferable to enlisting an unusual ->get_policy.

OK, I'll set VM_MIXEDMAP then.

I am still curious though why you feel get_policy is not appropriate
here (beside the fact that so far it had limited use). It is essentially
trying to say that the only policy to be consulted (in vma_policy_mof())
is of the vma itself and not of the task.

-boris

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH v3 (re-send)] xen/gntdev: Use mempolicy instead of VM_IO flag to avoid NUMA balancing Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-11-17 21:10 +0100
  Re: [PATCH v3 (re-send)] xen/gntdev: Use mempolicy instead of VM_IO  flag to avoid NUMA balancing Olaf Hering <olaf@aepfle.de> - 2016-11-18 09:10 +0100
  Re: [PATCH v3 (re-send)] xen/gntdev: Use mempolicy instead of VM_IO  flag to avoid NUMA balancing Hugh Dickins <hughd@google.com> - 2016-11-18 23:00 +0100
    Re: [PATCH v3 (re-send)] xen/gntdev: Use mempolicy instead of VM_IO  flag to avoid NUMA balancing Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-11-18 23:20 +0100
      Re: [PATCH v3 (re-send)] xen/gntdev: Use mempolicy instead of VM_IO  flag to avoid NUMA balancing Hugh Dickins <hughd@google.com> - 2016-11-18 23:30 +0100
        Re: [PATCH v3 (re-send)] xen/gntdev: Use mempolicy instead of VM_IO  flag to avoid NUMA balancing Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-11-18 23:50 +0100
          Re: [PATCH v3 (re-send)] xen/gntdev: Use mempolicy instead of VM_IO  flag to avoid NUMA balancing Hugh Dickins <hughd@google.com> - 2016-11-19 00:30 +0100

csiph-web