Bug 437167

Summary:	Need NUMA content in Realtime Tuning Guide
Product:	Red Hat Enterprise MRG	Reporter:	Clark Williams <williams>
Component:	Realtime_Tuning_Guide	Assignee:	Lana Brindley <lbrindle>
Status:	CLOSED NEXTRELEASE	QA Contact:	Jeff Needle <jneedle>
Severity:	low	Docs Contact:
Priority:	low
Version:	beta	CC:	bhu, dshaks, gbiswell, jonathan.robie, mhideo, sghosh
Target Milestone:	---	Keywords:	Documentation
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2008-05-29 03:27:01 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description Clark Williams 2008-03-12 18:30:28 UTC

Description of problem:

NUMA (Non-Uniform Memory Access) systems can interact badly with realtime
applications by causing unexpected event latencies. We need tuning content that
is specific to dealing with NUMA hardware.

Comment 1 Lana Brindley 2008-03-27 00:47:09 UTC

Added the following section to the "Realtime Tuning" chapter, until more info
received:

<section
id="sect-Realtime_Tuning_Guide-Realtime_Specific_Tuning-Non_Uniform_Memory_Access">
<title>Non-Uniform Memory Access</title>
<para>
Non-Uniform Memory Access (NUMA) is a design used to allocate memory resources
to a specific CPU. This can improve access time and results in fewer memory
locks. Although this sounds like it would be useful for reducing latency, NUMA
systems have been known to interact badly with realtime applications, as they
can cause unexpected event latencies.
</para>
<para>
For more information about the NUMA API, see Andi Kleen&#39;s whitepaper <ulink
url="http://www.halobates.de/numaapi3.pdf">An NUMA API for Linux</ulink>.
</para>
</section>

LKB

Comment 3 Lana Brindley 2008-05-05 23:47:47 UTC

If no further information on this section received by Friday 16 May, then
information currently in the guide will be assumed to be correct. Any further
information/updates to occur in the 1.1 docs.

LKB

Comment 6 Clark Williams 2008-05-16 21:47:50 UTC

Shak,

So, what does BIOS interleaving actually do? And is that what it's always going
to be called in the BIOS setup screen(s)? 

We're trying to get something together for user consumption that will give them
an idea of how to setup their system for RT, so the language needs to be clear.

Comment 7 Lana Brindley 2008-05-29 03:27:01 UTC

Closing this bug for now. Any further edits/additions to this section to be
included in 1.1 docs (a new bug will be required in that case).

LKB