Re: [PATCH v7] swiotlb: Adjust SWIOTBL bounce buffer size for SEV guests.

From: Borislav Petkov
Date: Mon Dec 07 2020 - 17:15:45 EST


On Mon, Dec 07, 2020 at 10:06:24PM +0000, Ashish Kalra wrote:
> This is related to the earlier static adjustment of the SWIOTLB buffers
> as per guest memory size and Konrad's feedback on the same, as copied
> below :
>
> >>That is eating 128MB for 1GB, aka 12% of the guest memory allocated statically for this.
> >>
> >> And for guests that are 2GB, that is 12% until it gets to 3GB when
> >> it is 8% and then 6% at 4GB.
> >>
> >> I would prefer this to be based on your memory count, that is 6% of
> >> total memory.

So no rule of thumb and no measurements? Just a magic number 6.

Btw, pls trim the rest of the mail when you reply. Like I just did.
There's no need to leave text which you're not responding to, quoted.

Thx.

--
Regards/Gruss,
Boris.

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