George Dunlap
2012-Sep-24 15:19 UTC
[PATCH] docs: Document scheduler-related Xen command-line options
# HG changeset patch # User George Dunlap <george.dunlap@eu.citrix.com> # Date 1348499935 -3600 # Node ID 7e332fd064fac8d9d1cea904d5236c8d74389194 # Parent 7b045d43e59dcb42340097058502bf456e151180 docs: Document scheduler-related Xen command-line options Signed-off-by: George Dunlap <george.dunlap@eu.citrix.com> diff --git a/docs/misc/xen-command-line.markdown b/docs/misc/xen-command-line.markdown --- a/docs/misc/xen-command-line.markdown +++ b/docs/misc/xen-command-line.markdown @@ -732,12 +732,34 @@ Choose the default scheduler. ### sched\_credit\_tslice\_ms > `= <integer>` +Set the timeslice of the credit1 scheduler, in milliseconds. The +default is 30ms. Reasonable values may include 10, 5, or even 1 for +very latency-sensitive workloads. + ### sched\_ratelimit\_us > `= <integer>` +In order to limit the rate of context switching, set the minimum +amount of time that a vcpu can be scheduled for before preempting it, +in microseconds. The default is 1000us (1ms). Setting this to 0 +disables it altogether. + ### sched\_smt\_power\_savings > `= <boolean>` +Normally Xen will try to maximize performance and cache utilization by +spreading out vcpus across as many different divisions as possible +(i.e, numa nodes, sockets, cores threads, &c). This often maximizes +throughput, but also maximizes energy usage, since it reduces the +depth to which a processor can sleep. + +This option inverts the logic, so that the scheduler in effect tries +to keep the vcpus on the smallest amount of silicon possible; i.e., +first fill up sibling threads, then sibling cores, then sibling +sockets, &c. This will reduce performance somewhat, particularly on +systems with hyperthreading enabled, but should reduce power by +enabling more sockets and cores to go into deeper sleep states. + ### serial\_tx\_buffer > `= <size>`
Ian Campbell
2012-Sep-25 15:18 UTC
Re: [PATCH] docs: Document scheduler-related Xen command-line options
On Mon, 2012-09-24 at 16:19 +0100, George Dunlap wrote:> # HG changeset patch > # User George Dunlap <george.dunlap@eu.citrix.com> > # Date 1348499935 -3600 > # Node ID 7e332fd064fac8d9d1cea904d5236c8d74389194 > # Parent 7b045d43e59dcb42340097058502bf456e151180 > docs: Document scheduler-related Xen command-line options > > Signed-off-by: George Dunlap <george.dunlap@eu.citrix.com>Acked-by: Ian Campbell <ian.campbell@citrix.com>> > diff --git a/docs/misc/xen-command-line.markdown b/docs/misc/xen-command-line.markdown > --- a/docs/misc/xen-command-line.markdown > +++ b/docs/misc/xen-command-line.markdown > @@ -732,12 +732,34 @@ Choose the default scheduler. > ### sched\_credit\_tslice\_ms > > `= <integer>` > > +Set the timeslice of the credit1 scheduler, in milliseconds. The > +default is 30ms. Reasonable values may include 10, 5, or even 1 for > +very latency-sensitive workloads. > + > ### sched\_ratelimit\_us > > `= <integer>` > > +In order to limit the rate of context switching, set the minimum > +amount of time that a vcpu can be scheduled for before preempting it, > +in microseconds. The default is 1000us (1ms). Setting this to 0 > +disables it altogether. > + > ### sched\_smt\_power\_savings > > `= <boolean>` > > +Normally Xen will try to maximize performance and cache utilization by > +spreading out vcpus across as many different divisions as possible > +(i.e, numa nodes, sockets, cores threads, &c). This often maximizes > +throughput, but also maximizes energy usage, since it reduces the > +depth to which a processor can sleep. > + > +This option inverts the logic, so that the scheduler in effect tries > +to keep the vcpus on the smallest amount of silicon possible; i.e., > +first fill up sibling threads, then sibling cores, then sibling > +sockets, &c. This will reduce performance somewhat, particularly on > +systems with hyperthreading enabled, but should reduce power by > +enabling more sockets and cores to go into deeper sleep states. > + > ### serial\_tx\_buffer > > `= <size>` > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xen.org > http://lists.xen.org/xen-devel
Ian Jackson
2012-Oct-01 16:50 UTC
Re: [PATCH] docs: Document scheduler-related Xen command-line options
George Dunlap writes ("[Xen-devel] [PATCH] docs: Document scheduler-related
Xen command-line options"):> docs: Document scheduler-related Xen command-line options
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>
Ian.