From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dario Faggioli Subject: Re: [PATCH RFC 1/2] linux/vnuma: vnuma support for pv guest Date: Thu, 29 Aug 2013 00:21:40 +0200 Message-ID: <1377728500.5255.51.camel@Abyss> References: <1377593580-10040-1-git-send-email-ufimtseva@gmail.com> <1377593580-10040-2-git-send-email-ufimtseva@gmail.com> <20130828012713.GA2840@u109add4315675089e695.ant.amazon.com> <20130828013733.GB2840@u109add4315675089e695.ant.amazon.com> <20130828160148.GE16368@phenom.dumpdata.com> <20130828163824.GA19277@u109add4315675089e695.ant.amazon.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============0196612327033769670==" Return-path: In-Reply-To: <20130828163824.GA19277@u109add4315675089e695.ant.amazon.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Matt Wilson Cc: George Dunlap , xen-devel@lists.xen.org, David Vrabel , Elena Ufimtseva List-Id: xen-devel@lists.xenproject.org --===============0196612327033769670== Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-uzDiXIEnadechDHY0D5N" --=-uzDiXIEnadechDHY0D5N Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On mer, 2013-08-28 at 09:38 -0700, Matt Wilson wrote: > On Wed, Aug 28, 2013 at 12:01:48PM -0400, Konrad Rzeszutek Wilk wrote: > > That would also parallel the work you do with ACPI right? >=20 > Yes. >=20 I see. It's hard to comment, since I have only seen some previous (off list) versiona of Elena's code (and won't have time to properly review this one untill Monday), and I haven't seen Matt's code at all...=20 Anyway... > > We could enable ACPI parsing in a PV guest and provide one table - the > > SLIT (or SRAT). >=20 > Right, it'd be the SRAT table for the resource affinity and a SLIT > table for the locality/distance information. >=20 ... I see the point in sharing code for HVM and PV. However, I'm still not convinced this would be something valuable to do with this specific hunk, mostly because it looks really easy and clean to hook up at the numa_init() stage (i.e., what Elena is doing), that anything else I can think of looks like more work. :-P > > But I don't know enough about SRAT to know whether this is something > > that represents truly everything we need? >=20 > The SRAT table has processor objects and memory objects. A processor > object maps a logical processor number to its initial APIC ID and > provides the node information. A memory object specifies the start and > length for a memory region and provides the node information. >=20 > For SLIT, the entries are a matrix of distances. >=20 > Here are the structs: >=20 > [snip] > Ok, thanks for the very useful info. What would be interesting to know is where and how Linux reads the information from ACPI and fill these structures. The current Elena's approach is 1 hypercall, during early NUMA initialization, and that is pretty self-contained (which is the thing I like most about it). How easy is it to look up the places where each one of the tables gets filled, intercept the code/calls doing that, and replace it properly for our use case? How easy is it to "xen-ify" those call sites (stuff like '#ifdef CONFIG_XEN' or/and is_xen_domain() )? How many hypercalls would it require? Is it possible to have one doing all the work, or would we need something like one for each table? As I said, I can't check the details about it right now, but it sounds like more work than Elena's xen_numa_init(). Thanks and Regards, Dario --=20 <> (Raistlin Majere) ----------------------------------------------------------------- Dario Faggioli, Ph.D, http://about.me/dario.faggioli Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK) --=-uzDiXIEnadechDHY0D5N Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.14 (GNU/Linux) iEYEABECAAYFAlIed/QACgkQk4XaBE3IOsTxdACfdpTSpqTf/Q6VXzCF35pPRslB C6QAoImM0mIuxb2Ql+vK3TI0ALTSBIot =il6r -----END PGP SIGNATURE----- --=-uzDiXIEnadechDHY0D5N-- --===============0196612327033769670== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel --===============0196612327033769670==--