linux-kernel - Re: [External] Re: [PATCH] vduse: Use fixed 4KB bounce pages for arm64 64KB page size

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Message-ID: <328b3f8f-cca7-4d8f-9335-24341b40b2d5@bytedance.com>
Date: Mon, 15 Sep 2025 19:07:47 +0800
From: Sheng Zhao <sheng.zhao@...edance.com>
To: Jason Wang <jasowang@...hat.com>
Cc: mst@...hat.com, xuanzhuo@...ux.alibaba.com, eperezma@...hat.com,
 virtualization@...ts.linux.dev, linux-kernel@...r.kernel.org,
 xieyongji@...edance.com
Subject: Re: [External] Re: [PATCH] vduse: Use fixed 4KB bounce pages for
 arm64 64KB page size



在 2025/9/15 16:21, Jason Wang 写道:
> On Mon, Sep 15, 2025 at 3:34 PM <sheng.zhao@...edance.com> wrote:
>>
>> From: Sheng Zhao <sheng.zhao@...edance.com>
>>
>> The allocation granularity of bounce pages is PAGE_SIZE. This may cause
>> even small IO requests to occupy an entire bounce page exclusively.
> 
> This sounds more like an issue of the IOVA allocating that use the
> wrong granular?
> 

Sorry, the previous email has a slight formatting issue.

The granularity of the IOVA allocator is customized during the 
initialization of the vduse domain, and this value is also modified in
this commit.

Thanks

>> The
>> kind of memory waste will be more significant on arm64 with 64KB pages.
>>
>> So, optimize it by using fixed 4KB bounce pages.
>>
>> Signed-off-by: Sheng Zhao <sheng.zhao@...edance.com>
> 
> Thanks
>