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

KOSAKI Motohiro
2013-10-08T04:35:37Z

(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.