linux-kernel - Re: [RFC][PATCH 2/6] x86: introduce cpumask specifically for the package

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20140918145757.GR2840@worktop.localdomain>
Date:	Thu, 18 Sep 2014 16:57:57 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Dave Hansen <dave@...1.net>
Cc:	mingo@...nel.org, hpa@...ux.intel.com, brice.goglin@...il.com,
	bp@...en8.de, linux-kernel@...r.kernel.org,
	dave.hansen@...ux.intel.com
Subject: Re: [RFC][PATCH 2/6] x86: introduce cpumask specifically for the
 package

On Wed, Sep 17, 2014 at 03:33:14PM -0700, Dave Hansen wrote:
> 
> From: Dave Hansen <dave.hansen@...ux.intel.com>
> 
> As noted by multiple reports:
> 
> 	https://lkml.org/lkml/2014/9/15/1240
> 	https://lkml.org/lkml/2014/7/28/442
> 
> the sched domains code has some assumptions that break on newer
> AMD and Intel CPUs.  Namely, the code assumes that NUMA node
> boundaries always lie outside of a CPU package.  That assumption
> is no longer true with Intel's Cluster-on-Die found in Haswell
> CPUs (with a special BIOS config knob) and AMD's DCM feature.
> 
> Essentially, the 'cpu_core_map' is no longer suitable for
> enumerating all the CPUs in a physical package.
> 
> This patch introduces a new map which is specifically built by
> consulting the the physical package ids instead of inferring the
> information from NUMA nodes.
> 
> This still leaves us with a broken 'core_siblings_list' in sysfs,
> but a later patch will fix that up too.

If we do dynamic topology layout we don't need a second mask I think.
The machines that have multiple packages per node will simply present a
different sched_domain_topology than the machines that have multiple
nodes per package.

Specifically, in the former we include the package_mask as DIE level, in
the other case we leave it out entirely and rely on the SLIT table to
build the right domain topology.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/