Re: [PATCH 05/14] vrange: Add new vrange(2) system call

[KOSAKI Motohiro]

(10/7/13 11:07 PM), Minchan Kim wrote:
> Hi KOSAKI,
>
> On Mon, Oct 07, 2013 at 10:51:18PM -0400, KOSAKI Motohiro wrote:
> > > Maybe, int madvise5(addr, length, MADV_DONTNEED|MADV_LAZY|MADV_SIGBUS,
> > >          &purged, &ret);
> > >
> > > Another reason to make it hard is that madvise(2) is tight coupled with
> > > with vmas split/merge. It needs mmap_sem's write-side lock and it hurt
> > > anon-vrange test performance much heavily and userland might want to
> > > make volatile range with small unit like "page size" so it's undesireable
> > > to make it with vma. Then, we should filter out to avoid vma split/merge
> > > in implementation if only MADV_LAZY case? Doable but it could make code
> > > complicated and lost consistency with other variant of madvise.
> >
> > I haven't seen your performance test result. Could please point out URLs?
>
> https://lkml.org/lkml/2013/3/12/105

It's not comparison with and without vma merge. I'm interest how much benefit
vmas operation avoiding have.

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