linux-kernel - Re: [RFC] perf_events: support for uncore a.k.a. nest units

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]

Date:	Wed, 20 Jan 2010 10:35:55 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Corey Ashford <cjashfor@...ux.vnet.ibm.com>
Cc:	Andi Kleen <andi@...stfloor.org>,
	LKML <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...e.hu>,
	Paul Mackerras <paulus@...ba.org>,
	Stephane Eranian <eranian@...glemail.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Xiao Guangrong <xiaoguangrong@...fujitsu.com>,
	Dan Terpstra <terpstra@...s.utk.edu>,
	Philip Mucci <mucci@...s.utk.edu>,
	Maynard Johnson <mpjohn@...ibm.com>, Carl Love <cel@...ibm.com>
Subject: Re: [RFC] perf_events: support for uncore a.k.a. nest units

> Yes, I agree.  Also it's easy to construct a system design that doesn't 
> have a hierarchical topology.  A simple example would be a cluster of 32 
> nodes, each of which is connected to its 31 neighbors.  Perhaps for the 

I doubt it's needed or useful to describe all details of an interconnect.

If detailed distance information is needed a simple table like
the SLIT table exported by ACPI would seem easier to handle.

But at least some degree of locality (e.g. "local memory controller")
would make sense.


> purposes of just enumerating PMUs, a tree might be sufficient, but it's not 
> clear to me that it is mathematically sufficient for all topologies, not to 
> mention if it's intuitive enough to use.  For example, 
> highly-interconnected components might require that PMU leaf nodes be 
> duplicated in multiple branches, i.e. PMU paths might not be unique in some 
> topologies.

We already have cyclical graphs in sysfs using symlinks. I'm not 
sure they are all that easy to parse/handle, but at least they
can be described.

-Andi

-- 
ak@...ux.intel.com -- Speaking for myself only.
--
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/