From: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>
To: "Hansen, Dave" <dave.hansen@intel.com>,
"Zhao, Yan Y" <yan.y.zhao@intel.com>
Cc: "kirill.shutemov@linux.intel.com"
<kirill.shutemov@linux.intel.com>,
"linux-coco@lists.linux.dev" <linux-coco@lists.linux.dev>,
"Huang, Kai" <kai.huang@intel.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"kas@kernel.org" <kas@kernel.org>,
"seanjc@google.com" <seanjc@google.com>,
"mingo@redhat.com" <mingo@redhat.com>,
"pbonzini@redhat.com" <pbonzini@redhat.com>,
"nik.borisov@suse.com" <nik.borisov@suse.com>,
"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
"hpa@zytor.com" <hpa@zytor.com>,
"Annapurve, Vishal" <vannapurve@google.com>,
"tglx@kernel.org" <tglx@kernel.org>,
"Gao, Chao" <chao.gao@intel.com>, "bp@alien8.de" <bp@alien8.de>,
"x86@kernel.org" <x86@kernel.org>
Subject: Re: [PATCH v6 06/11] x86/virt/tdx: Optimize tdx_pamt_get/put()
Date: Wed, 1 Jul 2026 01:45:24 +0000 [thread overview]
Message-ID: <173092378dcc803463b8d2af9f6f3ab6a908f77b.camel@intel.com> (raw)
In-Reply-To: <aiaQaCzL8o2yLu/2@yzhao56-desk.sh.intel.com>
Oh! You already did some testing.
On Mon, 2026-06-08 at 17:50 +0800, Yan Zhao wrote:
> > How important is this patch? I see "Optimize" but I read "Optional".
> This patch reduces the number of global pamt_lock acquisitions.
>
> Reference testing data with/without the optimization:
> (collected on my SPR test machine)
>
> Booting/teardown of 1 TD (8 vcpus/8G memory) per iteration:
> |--------------|-------------|------------|
> | avg (us) | max (us) | min (us) |
> | w/o | w/ | w/o | w/ | w/o | w/ |
> ----------------|-------|------|-------|-----|------|-----|
> __tdx_pamt_get()| 2 | 0 | 578 | 505 | 2 | 0 |
^ it looks like the old version. Is this on a huge page stack? Or just plain
dynamic PAMT?
> __tdx_pamt_put()| 0 | 0 | 563 | 496 | 0 | 0 |
> ----------------|--------------|-------------|------------|
>
> Boot/teardown of 5 TDs (each TD: 8 vcpus/8G memory) concurrently:
> |--------------|-------------|------------|
> | avg (us) | max (us) | min (us) |
> | w/o | w/ | w/o | w/ | w/o | w/ |
> ----------------|-------|------|-------|-----|------|-----|
> __tdx_pamt_get()| 15 | 0 | 1723 | 1386| 2 | 0 |
> __tdx_pamt_put()| 0 | 0 | 562 | 733| 0 | 0 |
> ----------------|--------------|-------------|------------|
Did you record total time, or number of invocations that we could use to turn
this into some more real world impact?
next prev parent reply other threads:[~2026-07-01 1:46 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-26 2:35 [PATCH v6 00/11] Dynamic PAMT Rick Edgecombe
2026-05-26 2:35 ` [PATCH v6 01/11] x86/virt/tdx: Simplify tdmr_get_pamt_sz() Rick Edgecombe
2026-06-04 16:05 ` Kiryl Shutsemau
2026-07-01 0:08 ` Edgecombe, Rick P
2026-06-11 18:25 ` Vishal Annapurve
2026-05-26 2:35 ` [PATCH v6 02/11] x86/virt/tdx: Allocate page bitmap for Dynamic PAMT Rick Edgecombe
2026-06-04 16:14 ` Kiryl Shutsemau
2026-07-01 0:14 ` Edgecombe, Rick P
2026-06-11 18:47 ` Vishal Annapurve
2026-05-26 2:35 ` [PATCH v6 03/11] x86/virt/tdx: Add tdx_alloc/free_control_page() helpers Rick Edgecombe
2026-06-08 2:11 ` Binbin Wu
2026-06-08 2:18 ` Yan Zhao
2026-07-01 0:15 ` Edgecombe, Rick P
2026-05-26 2:35 ` [PATCH v6 04/11] x86/virt/tdx: Allocate ref counts for Dynamic PAMT memory Rick Edgecombe
2026-07-02 7:20 ` Binbin Wu
2026-05-26 2:35 ` [PATCH v6 05/11] x86/virt/tdx: Handle concurrent callers in tdx_pamt_get/put() Rick Edgecombe
2026-07-02 7:39 ` Binbin Wu
2026-05-26 2:35 ` [PATCH v6 06/11] x86/virt/tdx: Optimize tdx_pamt_get/put() Rick Edgecombe
2026-05-26 8:57 ` Chao Gao
2026-05-26 16:42 ` Edgecombe, Rick P
2026-06-04 16:59 ` Kiryl Shutsemau
2026-06-05 5:40 ` Chao Gao
2026-06-05 11:42 ` Kiryl Shutsemau
2026-06-05 16:23 ` Dave Hansen
2026-06-08 9:14 ` Kiryl Shutsemau
2026-06-08 9:50 ` Yan Zhao
2026-07-01 1:45 ` Edgecombe, Rick P [this message]
2026-07-01 5:37 ` Yan Zhao
2026-07-01 1:05 ` Edgecombe, Rick P
2026-05-26 2:35 ` [PATCH v6 07/11] KVM: TDX: Allocate PAMT memory for TD and vCPU control structures Rick Edgecombe
2026-05-26 2:35 ` [PATCH v6 08/11] x86/tdx: Add APIs to support Dynamic PAMT ops from KVM's fault path Rick Edgecombe
2026-06-04 17:11 ` Kiryl Shutsemau
2026-05-26 2:35 ` [PATCH v6 09/11] KVM: TDX: Get/put PAMT pages when (un)mapping private memory Rick Edgecombe
2026-05-26 2:35 ` [PATCH v6 10/11] x86/virt/tdx: Enable Dynamic PAMT Rick Edgecombe
2026-06-04 17:14 ` Kiryl Shutsemau
2026-06-05 5:25 ` Chao Gao
2026-07-01 1:20 ` Edgecombe, Rick P
2026-05-26 2:35 ` [PATCH v6 11/11] Documentation/x86: Add documentation for TDX's " Rick Edgecombe
2026-06-08 5:45 ` [PATCH v6 00/11] " Tony Lindgren
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=173092378dcc803463b8d2af9f6f3ab6a908f77b.camel@intel.com \
--to=rick.p.edgecombe@intel.com \
--cc=bp@alien8.de \
--cc=chao.gao@intel.com \
--cc=dave.hansen@intel.com \
--cc=hpa@zytor.com \
--cc=kai.huang@intel.com \
--cc=kas@kernel.org \
--cc=kirill.shutemov@linux.intel.com \
--cc=kvm@vger.kernel.org \
--cc=linux-coco@lists.linux.dev \
--cc=linux-doc@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=nik.borisov@suse.com \
--cc=pbonzini@redhat.com \
--cc=seanjc@google.com \
--cc=tglx@kernel.org \
--cc=vannapurve@google.com \
--cc=x86@kernel.org \
--cc=yan.y.zhao@intel.com \
/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