# HG changeset patch
# User ack@xxxxxxxxxxxxxxxxxxxxxxx
# Node ID 6d476981e3a5da8198f726dfb34904d33dea4f40
# Parent 444abe25611f151194e042539bc9c76404cfccbd
Update docs for new credit scheduler and cleanup out of date scheduler stuff.
Signed-off-by: Emmanuel Ackaouy <ack@xxxxxxxxxxxxx>
---
docs/src/interface.tex | 29 +++++++++++------------------
docs/src/user.tex | 32 +++++++++++++++++++++++++++++++-
2 files changed, 42 insertions(+), 19 deletions(-)
diff -r 444abe25611f -r 6d476981e3a5 docs/src/interface.tex
--- a/docs/src/interface.tex Sun May 28 09:46:30 2006 +0100
+++ b/docs/src/interface.tex Sun May 28 15:49:17 2006 +0100
@@ -205,30 +205,23 @@ implement timeout values when they block
implement timeout values when they block.
-
-%% % akw: demoting this to a section -- not sure if there is any point
-%% % though, maybe just remove it.
-
-% KAF: Remove these random sections!
-\begin{comment}
\section{Xen CPU Scheduling}
Xen offers a uniform API for CPU schedulers. It is possible to choose
from a number of schedulers at boot and it should be easy to add more.
-The BVT, Atropos and Round Robin schedulers are part of the normal Xen
-distribution. BVT provides proportional fair shares of the CPU to the
-running domains. Atropos can be used to reserve absolute shares of
-the CPU for each domain. Round-robin is provided as an example of
-Xen's internal scheduler API.
+The SEDF, BVT, and Credit schedulers are part of the normal Xen
+distribution. BVT and SEDF will be going away and their use should be
+avoided once the credit scheduler has stabilized and become the default.
+The Credit scheduler provides proportional fair shares of the
+host's CPUs to the running domains. It does this while transparently
+load balancing runnable VCPUs across the whole system.
\paragraph*{Note: SMP host support}
-Xen has always supported SMP host systems. Domains are statically
-assigned to CPUs, either at creation time or when manually pinning to
-a particular CPU. The current schedulers then run locally on each CPU
-to decide which of the assigned domains should be run there. The
-user-level control software can be used to perform coarse-grain
-load-balancing between CPUs.
-\end{comment}
+Xen has always supported SMP host systems. When using the credit scheduler,
+a domain's VCPUs will be dynamically moved across physical CPUs to maximise
+domain and system throughput. VCPUs can also be manually restricted to be
+mapped only on a subset of the host's physical CPUs, using the pinning
+mechanism.
%% More information on the characteristics and use of these schedulers
diff -r 444abe25611f -r 6d476981e3a5 docs/src/user.tex
--- a/docs/src/user.tex Sun May 28 09:46:30 2006 +0100
+++ b/docs/src/user.tex Sun May 28 15:49:17 2006 +0100
@@ -1093,6 +1093,36 @@ running domains in \xend's SXP configura
You can get access to the console of a particular domain using
the \verb_# xm console_ command (e.g.\ \verb_# xm console myVM_).
+
+\subsection{Domain Scheduling Management Commands}
+
+The credit CPU scheduler automatically load balances guest VCPUs
+across all available physical CPUs on an SMP host. The user need
+not manually pin VCPUs to load balance the system. However, she
+can restrict which CPUs a particular VCPU may run on using
+the \path{xm vcpu-pin} command.
+
+Each guest domain is assigned a \path{weight} and a \path{cap}.
+
+A domain with a weight of 512 will get twice as much CPU as a
+domain with a weight of 256 on a contended host. Legal weights
+range from 1 to 65535 and the default is 256.
+
+The cap optionally fixes the maximum amount of CPU a guest will
+be able to consume, even if the host system has idle CPU cycles.
+The cap is expressed in percentage of one physical CPU: 100 is
+1 physical CPU, 50 is half a CPU, 400 is 4 CPUs, etc... The
+default, 0, means there is no upper cap.
+
+When you are running with the credit scheduler, you can check and
+modify your domains' weights and caps using the \path{xm sched-credit}
+command:
+
+\begin{tabular}{ll}
+\verb!xm sched-credit -d <domain>! & lists weight and cap \\
+\verb!xm sched-credit -d <domain> -w <weight>! & sets the weight \\
+\verb!xm sched-credit -d <domain> -c <cap>! & sets the cap
+\end{tabular}
@@ -1985,7 +2015,7 @@ editing \path{grub.conf}.
\item [ tbuf\_size=xxx ] Set the size of the per-cpu trace buffers, in
pages (default 0).
\item [ sched=xxx ] Select the CPU scheduler Xen should use. The
- current possibilities are `sedf' (default) and `bvt'.
+ current possibilities are `sedf' (default), `credit', and `bvt'.
\item [ apic\_verbosity=debug,verbose ] Print more detailed
information about local APIC and IOAPIC configuration.
\item [ lapic ] Force use of local APIC even when left disabled by
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