On Fri, 24 Oct 2014, Peter Zijlstra wrote:
> The hold time isn't relevant, in fact breaking up the mmap_sem such that
> we require multiple acquisitions will just increase the cacheline
> bouncing.
Well this wont be happening anymore once you RCUify the stuff. If you go
to sleep then its best to
On Fri, Oct 24, 2014 at 10:16:24AM -0500, Christoph Lameter wrote:
> Hmmm... One optimization to do before we get into these changes is to work
> on allowing the dropping of mmap_sem before we get to sleeping and I/O and
> then reevaluate when I/O etc is complete? This is probably the longest
> ho
On Tue, 21 Oct 2014, Peter Zijlstra wrote:
> On Mon, Oct 20, 2014 at 04:41:45PM -0700, Linus Torvalds wrote:
> > On Mon, Oct 20, 2014 at 2:56 PM, Peter Zijlstra
> > wrote:
> > > Manage the VMAs with SRCU such that we can do a lockless VMA lookup.
> >
> > Can you explain why srcu, and not plain r
On Fri, Oct 24, 2014 at 11:33:58AM +0800, Lai Jiangshan wrote:
> On 10/23/2014 07:03 PM, Peter Zijlstra wrote:
> > On Thu, Oct 23, 2014 at 06:14:45PM +0800, Lai Jiangshan wrote:
> >>
> >>>
> >>> +struct vm_area_struct *find_vma_srcu(struct mm_struct *mm, unsigned long
> >>> addr)
> >>> +{
> >>>
On 10/23/2014 07:03 PM, Peter Zijlstra wrote:
> On Thu, Oct 23, 2014 at 06:14:45PM +0800, Lai Jiangshan wrote:
>>
>>>
>>> +struct vm_area_struct *find_vma_srcu(struct mm_struct *mm, unsigned long
>>> addr)
>>> +{
>>> + struct vm_area_struct *vma;
>>> + unsigned int seq;
>>> +
>>> + WARN_ON
On Thu, Oct 23, 2014 at 06:14:45PM +0800, Lai Jiangshan wrote:
>
> >
> > +struct vm_area_struct *find_vma_srcu(struct mm_struct *mm, unsigned long
> > addr)
> > +{
> > + struct vm_area_struct *vma;
> > + unsigned int seq;
> > +
> > + WARN_ON_ONCE(!srcu_read_lock_held(&vma_srcu));
> > +
>
>
> +struct vm_area_struct *find_vma_srcu(struct mm_struct *mm, unsigned long
> addr)
> +{
> + struct vm_area_struct *vma;
> + unsigned int seq;
> +
> + WARN_ON_ONCE(!srcu_read_lock_held(&vma_srcu));
> +
> + do {
> + seq = read_seqbegin(&mm->mm_seq);
> +
On Mon, Oct 20, 2014 at 04:41:45PM -0700, Linus Torvalds wrote:
> On Mon, Oct 20, 2014 at 2:56 PM, Peter Zijlstra wrote:
> > Manage the VMAs with SRCU such that we can do a lockless VMA lookup.
>
> Can you explain why srcu, and not plain regular rcu?
>
> Especially as you then *note* some of the
On Mon, Oct 20, 2014 at 04:41:45PM -0700, Linus Torvalds wrote:
> On Mon, Oct 20, 2014 at 2:56 PM, Peter Zijlstra wrote:
> > Manage the VMAs with SRCU such that we can do a lockless VMA lookup.
>
> Can you explain why srcu, and not plain regular rcu?
>
> Especially as you then *note* some of the
On Mon, Oct 20, 2014 at 2:56 PM, Peter Zijlstra wrote:
> Manage the VMAs with SRCU such that we can do a lockless VMA lookup.
Can you explain why srcu, and not plain regular rcu?
Especially as you then *note* some of the problems srcu can have.
Making it regular rcu would also seem to make it po
Manage the VMAs with SRCU such that we can do a lockless VMA lookup.
We put the fput(vma->vm_file) in the SRCU callback, this keeps files
valid during speculative faults, this is possible due to the delayed
fput work by Al Viro -- do we need srcu_barrier() in unmount
someplace?
We guard the mm_rb
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