From: Borislav Petkov <bp@alien8.de>
To: "Kalra, Ashish" <Ashish.Kalra@amd.com>
Cc: "Lendacky, Thomas" <Thomas.Lendacky@amd.com>,
"Grimm, Jon" <Jon.Grimm@amd.com>,
"Singh, Brijesh" <brijesh.singh@amd.com>,
"dave.hansen@linux-intel.com" <dave.hansen@linux-intel.com>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
"peterz@infradead.org" <peterz@infradead.org>,
"x86@kernel.org" <x86@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>,
"mingo@redhat.com" <mingo@redhat.com>,
"luto@kernel.org" <luto@kernel.org>,
"hpa@zytor.com" <hpa@zytor.com>,
"rientjes@google.com" <rientjes@google.com>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"hch@lst.de" <hch@lst.de>
Subject: Re: [PATCH v6] swiotlb: Adjust SWIOTBL bounce buffer size for SEV guests.
Date: Tue, 24 Nov 2020 10:38:37 +0100 [thread overview]
Message-ID: <20201124093837.GD4009@zn.tnic> (raw)
In-Reply-To: <EF13C80C-42DC-4B51-8AF8-2C1D3859B490@amd.com>
On Tue, Nov 24, 2020 at 09:25:06AM +0000, Kalra, Ashish wrote:
> But what will be the criteria to figure out this percentage?
>
> As I mentioned earlier, this can be made as complicated as possible by
> adding all kind of heuristics but without any predictable performance
> gain.
>
> Or it can be kept simple by using a static percentage value.
Yes, static percentage number based on the guest memory. X% of the guest
memory is used for SWIOTLB.
Since you use sev_active(), it means the size computation is done in the
guest so that SWIOTLB size is per-guest. Yes?
If so, you can simply take, say, 5% of the guest memory's size and use
that for SWIOTLB buffers. Or 6 or X or whatever.
Makes sense?
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
next prev parent reply other threads:[~2020-11-24 9:38 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-19 21:42 [PATCH v6] swiotlb: Adjust SWIOTBL bounce buffer size for SEV guests Ashish Kalra
2020-11-23 17:06 ` Borislav Petkov
2020-11-23 17:56 ` Konrad Rzeszutek Wilk
2020-11-23 18:02 ` Borislav Petkov
2020-11-23 18:43 ` Konrad Rzeszutek Wilk
2020-11-24 9:00 ` Borislav Petkov
2020-11-23 22:56 ` Ashish Kalra
2020-11-24 9:04 ` Borislav Petkov
2020-11-24 9:25 ` Kalra, Ashish
2020-11-24 9:38 ` Borislav Petkov [this message]
2020-11-24 9:43 ` Kalra, Ashish
2020-11-24 23:46 ` Ashish Kalra
2020-12-01 20:42 ` Konrad Rzeszutek Wilk
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20201124093837.GD4009@zn.tnic \
--to=bp@alien8.de \
--cc=Ashish.Kalra@amd.com \
--cc=Jon.Grimm@amd.com \
--cc=Thomas.Lendacky@amd.com \
--cc=brijesh.singh@amd.com \
--cc=dave.hansen@linux-intel.com \
--cc=hch@lst.de \
--cc=hpa@zytor.com \
--cc=iommu@lists.linux-foundation.org \
--cc=konrad.wilk@oracle.com \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@kernel.org \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=rientjes@google.com \
--cc=tglx@linutronix.de \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).