From: Andi Kleen <ak@linux.intel.com>
To: Dave Hansen <dave.hansen@intel.com>,
"Kirill A. Shutemov" <kirill@shutemov.name>,
Borislav Petkov <bp@alien8.de>, Andy Lutomirski <luto@kernel.org>,
Sean Christopherson <seanjc@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Joerg Roedel <jroedel@suse.de>
Cc: Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@linux.intel.com>,
David Rientjes <rientjes@google.com>,
Vlastimil Babka <vbabka@suse.cz>,
Tom Lendacky <thomas.lendacky@amd.com>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Paolo Bonzini <pbonzini@redhat.com>,
Ingo Molnar <mingo@redhat.com>,
Varad Gautam <varad.gautam@suse.com>,
Dario Faggioli <dfaggioli@suse.com>,
x86@kernel.org, linux-mm@kvack.org, linux-coco@lists.linux.dev,
linux-kernel@vger.kernel.org,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: Re: [PATCH 1/5] mm: Add support for unaccepted memory
Date: Tue, 10 Aug 2021 12:23:48 -0700 [thread overview]
Message-ID: <796a4b20-7fa3-3086-efa0-2f728f35ae06@linux.intel.com> (raw)
In-Reply-To: <17b6a3a3-bd7d-f57e-8762-96258b16247a@intel.com>
> But, not everyone is going to agree with me.
Both the Intel TDX and the AMD SEV side independently came to opposite
conclusions. In general people care a lot about boot time of VM guests.
>
> This also begs the question of how folks know when this "blip" is over.
> Do we have a counter for offline pages? Is there any way to force page
> acceptance? Or, are we just stuck allocating a bunch of memory to warm
> up the system?
>
> How do folks who care about these new blips avoid them?
It's not different than any other warmup. At warmup time you always have
lots of blips until the working set stabilizes. For example in
virtualization first touch of a new page is usually an EPT violation
handled to the host. Or in the native case you may need to do IO or free
memory. Everybody who based their critical latency percentiles around a
warming up process would be foolish, the picture would be completely
distorted.
So the basic operation is adding some overhead, but I don't think
anything is that unusual compared to the state of the art.
Now perhaps the locking might be a problem if the other operations all
run in parallel, causing unnecessary serialization If that's really a
problem I guess we can optimize later. I don't think there's anything
fundamental about the current locking.
-Andi
next prev parent reply other threads:[~2021-08-10 19:23 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-10 6:26 [PATCH 0/5] x86: Impplement support for unaccepted memory Kirill A. Shutemov
2021-08-10 6:26 ` [PATCH 1/5] mm: Add " Kirill A. Shutemov
2021-08-10 7:48 ` David Hildenbrand
2021-08-10 15:02 ` Kirill A. Shutemov
2021-08-10 15:21 ` David Hildenbrand
2021-08-12 20:34 ` Kirill A. Shutemov
2021-08-10 18:13 ` Dave Hansen
2021-08-10 18:30 ` Andi Kleen
2021-08-10 18:56 ` Dave Hansen
2021-08-10 19:23 ` Andi Kleen [this message]
2021-08-10 19:46 ` Dave Hansen
2021-08-10 21:20 ` Andi Kleen
2021-08-12 8:19 ` Joerg Roedel
2021-08-12 14:14 ` Dave Hansen
2021-08-12 20:49 ` Kirill A. Shutemov
2021-08-12 20:59 ` Dave Hansen
2021-08-12 21:23 ` Kirill A. Shutemov
2021-08-13 14:49 ` Joerg Roedel
2021-08-17 15:00 ` David Hildenbrand
2021-08-19 9:55 ` Joerg Roedel
2021-08-19 10:06 ` David Hildenbrand
2021-08-10 20:50 ` Dave Hansen
2021-08-12 21:08 ` Kirill A. Shutemov
2021-08-10 6:26 ` [PATCH 2/5] efi/x86: Implement " Kirill A. Shutemov
2021-08-10 17:50 ` Dave Hansen
2021-08-12 21:14 ` Kirill A. Shutemov
2021-08-12 21:43 ` Dave Hansen
2021-08-10 18:30 ` Dave Hansen
2021-08-10 19:08 ` Kirill A. Shutemov
2021-08-10 19:19 ` Dave Hansen
2021-08-12 21:17 ` Kirill A. Shutemov
2021-08-10 6:26 ` [PATCH 3/5] x86/boot/compressed: Handle " Kirill A. Shutemov
2021-08-10 6:26 ` [PATCH 4/5] x86/mm: Provide helpers for " Kirill A. Shutemov
2021-08-10 18:16 ` Dave Hansen
2021-08-12 20:31 ` Kirill A. Shutemov
2021-08-10 6:26 ` [PATCH 5/5] x86/tdx: Unaccepted memory support Kirill A. Shutemov
2021-08-10 14:08 ` [PATCH 0/5] x86: Impplement support for unaccepted memory Dave Hansen
2021-08-10 15:15 ` Kirill A. Shutemov
2021-08-10 15:51 ` Dave Hansen
2021-08-10 17:31 ` Kirill A. Shutemov
2021-08-10 17:36 ` Dave Hansen
2021-08-10 17:51 ` Kirill A. Shutemov
2021-08-10 18:19 ` Dave Hansen
2021-08-10 18:39 ` Kirill A. Shutemov
2021-08-12 8:23 ` Joerg Roedel
2021-08-12 10:10 ` Kirill A. Shutemov
2021-08-12 19:33 ` Andi Kleen
2021-08-12 20:22 ` Kirill A. Shutemov
2021-08-13 14:56 ` Joerg Roedel
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