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From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>,
	linux-sgx@vger.kernel.org, kai.svahn@intel.com,
	bruce.schlobohm@intel.com
Subject: Re: [PATCH RFC] x86/sgx: Allocate form local NUMA node first
Date: Thu, 25 Jun 2020 05:57:38 +0300	[thread overview]
Message-ID: <20200625025738.GE270125@linux.intel.com> (raw)
In-Reply-To: <20200625005752.GI25092@linux.intel.com>

On Wed, Jun 24, 2020 at 05:57:52PM -0700, Sean Christopherson wrote:
> On Wed, Jun 24, 2020 at 05:25:59PM -0700, Dave Hansen wrote:
> > On 6/24/20 4:54 PM, Sean Christopherson wrote:
> > >> Does this actually work?
> > >>
> > >> The node span (->node_start_pfn through start+->node_spanned_pages) only
> > >> contains pages which the OS is actively managing, usually RAM but
> > >> sometimes also persistent memory.  This has some assumption that the SGX
> > >> PFNs are within the node's span.  I would only _expect_ that to happen
> > >> if the node was built like this:
> > >>
> > >> 	| Node-X RAM | EPC | Node-X RAM |
> > >>
> > >> If the EPC was on either end:
> > >>
> > >> 	| Node-X RAM | EPC |
> > >> or
> > >> 	| EPC | Node-X RAM |
> > >>
> > >> I suspect that the pgdat span wouldn't include EPC.  EPC is, if I
> > >> remember correctly, a E820_RESERVED region.
> > > It is indeed E820_RESERVED, but the BIOS WG for ICX states that EPC regions
> > > should be enumerated in ACPI SRAT along with regular memory.
> > > 
> > > But, I haven't actually verified that info makes its way into the kernel's
> > > pgdata stuff.
> > 
> > Considering this, are we all agreed that this patch is in no condition
> > to be submitted upstream?
> 
> Yes, it needs to be tested first.
> 
> I like the resulting code more than what we have now, but I see no reason to
> change it at this stage unless one of the maintainers actually complains.

I'm cool with this. I think that this patch shows that the current
candidate patch set (v33) is in a good shape: the diff adheres very
cleanly on what we have.

/Jarkko

      reply	other threads:[~2020-06-25  2:57 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-23  4:39 [PATCH RFC] x86/sgx: Allocate form local NUMA node first Jarkko Sakkinen
2020-06-24 23:12 ` Jarkko Sakkinen
2020-06-24 23:24 ` Dave Hansen
2020-06-24 23:54   ` Sean Christopherson
2020-06-25  0:25     ` Dave Hansen
2020-06-25  0:57       ` Sean Christopherson
2020-06-25  2:57         ` Jarkko Sakkinen [this message]

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