From: Mingwei Zhang <mizhang@google.com>
To: Jim Mattson <jmattson@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <seanjc@google.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Joerg Roedel <joro@8bytes.org>, kvm <kvm@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Ben Gardon <bgardon@google.com>,
David Matlack <dmatlack@google.com>,
Jing Zhang <jingzhangos@google.com>,
peterx@redhat.com
Subject: Re: [PATCH v4 3/3] KVM: x86/mmu: Add detailed page size stats
Date: Mon, 9 Aug 2021 17:01:39 -0700 [thread overview]
Message-ID: <CAL715WLO9+CpNa4ZQX4J2OdyqOBsX0+g0M4bNe+A+6FVxB2OxA@mail.gmail.com> (raw)
In-Reply-To: <CAL715WJLfJc3dnLUcMRY=wNPX0XDuL9WzF-4VWMdS_OudShXHg@mail.gmail.com>
Hi Paolo,
I recently looked at the patches queued and I find this patch from
Peter Xu (Cced), which is also adding 'page stats' information into
KVM:
https://patchwork.kernel.org/project/kvm/patch/20210625153214.43106-7-peterx@redhat.com/
From a functionality point of view, the above patch seems duplicate
with mine. But in detail, Peter's approach is using debugfs with
proper locking to traverse the whole rmap to get the detailed page
sizes in different granularity.
In comparison, mine is to add extra code in low level SPTE update
routines and store aggregated data in kvm->kvm_stats. This data could
be retrieved from Jing's fd based API without any lock required, but
it does not provide the fine granular information such as the number
of contiguous 4KG/2MB/1GB pages.
So would you mind giving me some feedback on this patch? I would
really appreciate it.
Thank you. Regards
-Mingwei
-Mingwei
On Mon, Aug 9, 2021 at 4:39 PM Mingwei Zhang <mizhang@google.com> wrote:
>
> Hi Jim,
>
> No, I don't think 512G is supported. So, I will remove the
> 'pages_512G' metric in my next version.
>
> Thanks.
> -Mingwei
>
> On Mon, Aug 9, 2021 at 3:26 PM Jim Mattson <jmattson@google.com> wrote:
> >
> > On Mon, Aug 2, 2021 at 9:46 PM Mingwei Zhang <mizhang@google.com> wrote:
> > >
> > > Existing KVM code tracks the number of large pages regardless of their
> > > sizes. Therefore, when large page of 1GB (or larger) is adopted, the
> > > information becomes less useful because lpages counts a mix of 1G and 2M
> > > pages.
> > >
> > > So remove the lpages since it is easy for user space to aggregate the info.
> > > Instead, provide a comprehensive page stats of all sizes from 4K to 512G.
> >
> > There is no such thing as a 512GiB page, is there? If this is an
> > attempt at future-proofing, why not go to 256TiB?
next prev parent reply other threads:[~2021-08-10 0:02 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-03 4:46 [PATCH v4 0/3] Add detailed page size stats in KVM stats Mingwei Zhang
2021-08-03 4:46 ` [PATCH v4 1/3] KVM: x86/mmu: Remove redundant spte present check in mmu_set_spte Mingwei Zhang
2021-08-03 4:46 ` [PATCH v4 2/3] KVM: x86/mmu: Avoid collision with !PRESENT SPTEs in TDP MMU lpage stats Mingwei Zhang
2021-08-03 4:46 ` [PATCH v4 3/3] KVM: x86/mmu: Add detailed page size stats Mingwei Zhang
2021-08-09 22:26 ` Jim Mattson
2021-08-09 23:39 ` Mingwei Zhang
2021-08-10 0:01 ` Mingwei Zhang [this message]
2021-08-10 23:22 ` Peter Xu
2021-08-11 1:06 ` Mingwei Zhang
2021-08-11 13:12 ` Peter Xu
2021-08-12 17:44 ` Mingwei Zhang
2021-08-11 11:36 ` Paolo Bonzini
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=CAL715WLO9+CpNa4ZQX4J2OdyqOBsX0+g0M4bNe+A+6FVxB2OxA@mail.gmail.com \
--to=mizhang@google.com \
--cc=bgardon@google.com \
--cc=dmatlack@google.com \
--cc=jingzhangos@google.com \
--cc=jmattson@google.com \
--cc=joro@8bytes.org \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=pbonzini@redhat.com \
--cc=peterx@redhat.com \
--cc=seanjc@google.com \
--cc=vkuznets@redhat.com \
--cc=wanpengli@tencent.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;
as well as URLs for NNTP newsgroup(s).