linux-kernel - Re: 答复: 答复: [PATCH V2] vfio dma_map/unmap: optimized for hugetlbfs pages

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Date:   Tue, 1 Sep 2020 10:40:29 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Peter Xu <peterx@...hat.com>,
        "Maoming (maoming, Cloud Infrastructure Service Product Dept.)" 
        <maoming.maoming@...wei.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "alex.williamson@...hat.com" <alex.williamson@...hat.com>,
        "cohuck@...hat.com" <cohuck@...hat.com>,
        "Zhoujian (jay)" <jianjay.zhou@...wei.com>,
        "Huangweidong (C)" <weidong.huang@...wei.com>,
        "aarcange@...hat.com" <aarcange@...hat.com>,
        wangyunjian <wangyunjian@...wei.com>
Subject: Re: 答复: 答复: [PATCH V2] vfio dma_map/unmap: optimized for hugetlbfs pages


On 2020/8/28 下午10:24, Peter Xu wrote:
> On Fri, Aug 28, 2020 at 09:23:08AM +0000, Maoming (maoming, Cloud Infrastructure Service Product Dept.) wrote:
>> In hugetlb_put_pfn(), I delete unpin_user_pages_dirty_lock() and use some simple code to put hugetlb pages.
>> Is this right?
> I think we should still use the APIs because of the the same reason.  However
> again I don't know the performance impact of that to your patch, but I still
> think that could be done inside gup itself when needed (e.g., a special path
> for hugetlbfs for [un]pinning continuous pages; though if that's the case that
> could be something to be discussed on -mm then as a separate patch, imho).
>
> Thanks,


+1, we should make this as a generic optimization instead of VFIO 
specific consider there're a lot of GUP users.

Thanks