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

[Jason Wang]

On Mon, Sep 15, 2025 at 7:07 PM Sheng Zhao <sheng.zhao@xxxxxxxxxxxxx> wrote:
>
>
>
> 在 2025/9/15 16:21, Jason Wang 写道:
> > On Mon, Sep 15, 2025 at 3:34 PM <sheng.zhao@xxxxxxxxxxxxx> wrote:
> >>
> >> From: Sheng Zhao <sheng.zhao@xxxxxxxxxxxxx>
> >>
> >> 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.

Ok, let's add this to the changelog.

Btw, do you have perf numbers to demonstrate the benefit?

Thanks

>
> 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@xxxxxxxxxxxxx>
> >
> > Thanks
> >
>