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From: "J. Bruce Fields" <bfields@fieldses.org>
To: Jonathan Corbet <corbet@lwn.net>
Cc: Randy Dunlap <rdunlap@xenotime.net>, linux-kernel@vger.kernel.org
Subject: [PATCH] Move sced-rt-group.txt to scheduler/
Date: Mon, 7 Apr 2008 16:31:58 -0400	[thread overview]
Message-ID: <20080407203158.GB11219@fieldses.org> (raw)
In-Reply-To: <26652.1207599992@vena.lwn.net>

From: J. Bruce Fields <bfields@citi.umich.edu>

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
---
 Documentation/sched-rt-group.txt |   59 --------------------------------------
 Documentation/scheduler/00-INDEX |    2 +
 2 files changed, 2 insertions(+), 59 deletions(-)
 delete mode 100644 Documentation/sched-rt-group.txt

On Mon, Apr 07, 2008 at 02:26:32PM -0600, Jonathan Corbet wrote:
> J. Bruce Fields <bfields@citi.umich.edu> wrote:
> 
> > These are just 3 small patches for your documentation tree.
> 
> Thanks; unless somebody objects I'll pull them in.  I may not resubmit
> the tree before 2.6.25 - got travel to do and it's not urgent - but I'll
> definitely put it up for the next merge window.

Thanks!  Oh, also, I just noticed one more.  But one could probably do
this all day....

--b.

diff --git a/Documentation/sched-rt-group.txt b/Documentation/sched-rt-group.txt
deleted file mode 100644
index 1c6332f..0000000
--- a/Documentation/sched-rt-group.txt
+++ /dev/null
@@ -1,59 +0,0 @@
-
-
-Real-Time group scheduling.
-
-The problem space:
-
-In order to schedule multiple groups of realtime tasks each group must
-be assigned a fixed portion of the CPU time available. Without a minimum
-guarantee a realtime group can obviously fall short. A fuzzy upper limit
-is of no use since it cannot be relied upon. Which leaves us with just
-the single fixed portion.
-
-CPU time is divided by means of specifying how much time can be spent
-running in a given period. Say a frame fixed realtime renderer must
-deliver 25 frames a second, which yields a period of 0.04s. Now say
-it will also have to play some music and respond to input, leaving it
-with around 80% for the graphics. We can then give this group a runtime
-of 0.8 * 0.04s = 0.032s.
-
-This way the graphics group will have a 0.04s period with a 0.032s runtime
-limit.
-
-Now if the audio thread needs to refill the DMA buffer every 0.005s, but
-needs only about 3% CPU time to do so, it can do with a 0.03 * 0.005s
-= 0.00015s.
-
-
-The Interface:
-
-system wide:
-
-/proc/sys/kernel/sched_rt_period_ms
-/proc/sys/kernel/sched_rt_runtime_us
-
-CONFIG_FAIR_USER_SCHED
-
-/sys/kernel/uids/<uid>/cpu_rt_runtime_us
-
-or
-
-CONFIG_FAIR_CGROUP_SCHED
-
-/cgroup/<cgroup>/cpu.rt_runtime_us
-
-[ time is specified in us because the interface is s32; this gives an
-  operating range of ~35m to 1us ]
-
-The period takes values in [ 1, INT_MAX ], runtime in [ -1, INT_MAX - 1 ].
-
-A runtime of -1 specifies runtime == period, ie. no limit.
-
-New groups get the period from /proc/sys/kernel/sched_rt_period_us and
-a runtime of 0.
-
-Settings are constrained to:
-
-   \Sum_{i} runtime_{i} / global_period <= global_runtime / global_period
-
-in order to keep the configuration schedulable.
diff --git a/Documentation/scheduler/00-INDEX b/Documentation/scheduler/00-INDEX
index b5f5ca0..fc234d0 100644
--- a/Documentation/scheduler/00-INDEX
+++ b/Documentation/scheduler/00-INDEX
@@ -12,5 +12,7 @@ sched-domains.txt
 	- information on scheduling domains.
 sched-nice-design.txt
 	- How and why the scheduler's nice levels are implemented.
+sched-rt-group.txt
+	- real-time group scheduling.
 sched-stats.txt
 	- information on schedstats (Linux Scheduler Statistics).
-- 
1.5.5.rc1


  reply	other threads:[~2008-04-07 20:32 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-04-07 19:59 miscellaneous documentation patches J. Bruce Fields
2008-04-07 19:59 ` [PATCH] Documentation: move nfsroot.txt to filesystems/ J. Bruce Fields
2008-04-07 19:59   ` [PATCH] Documentation: move rpc-cache.txt " J. Bruce Fields
2008-04-07 19:59     ` [PATCH] Spell out behavior of atomic_dec_and_lock() in kerneldoc J. Bruce Fields
2008-04-07 20:26 ` miscellaneous documentation patches Jonathan Corbet
2008-04-07 20:31   ` J. Bruce Fields [this message]
2008-04-07 20:39     ` [PATCH] Move sched-rt-group.txt to scheduler/ J. Bruce Fields

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