rpms/kernel/devel linux-2.6-sched-features-disable-hrtick.patch, NONE, 1.1 linux-2.6-sched_clock-prevent-scd-clock-from-moving-backwards, NONE, 1.1 TODO, 1.29, 1.30 kernel.spec, 1.1084, 1.1085

[Chuck Ebbert]

Author: cebbert

Update of /cvs/pkgs/rpms/kernel/devel
In directory cvs1.fedora.phx.redhat.com:/tmp/cvs-serv21357

Modified Files:
	TODO kernel.spec 
Added Files:
	linux-2.6-sched-features-disable-hrtick.patch 
	linux-2.6-sched_clock-prevent-scd-clock-from-moving-backwards 
Log Message:
Scheduler fixes from 2.6.28, fixing performance problems:
    Disable HRTICK scheduler feature.
    Keep the scheduler clock from going backwards.

linux-2.6-sched-features-disable-hrtick.patch:

--- NEW FILE linux-2.6-sched-features-disable-hrtick.patch ---
From: Ingo Molnar <mingo at elte.hu>
Date: Mon, 20 Oct 2008 12:27:43 +0000 (+0200)
Subject: sched: disable the hrtick for now
X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftorvalds%2Flinux-2.6.git;a=commitdiff_plain;h=0c4b83da58ec2e96ce9c44c211d6eac5f9dae478

sched: disable the hrtick for now

David Miller reported that hrtick update overhead has tripled the
wakeup overhead on Sparc64.

That is too much - disable the HRTICK feature for now by default,
until a faster implementation is found.

Reported-by: David Miller <davem at davemloft.net>
Acked-by: Peter Zijlstra <peterz at infradead.org>
Signed-off-by: Ingo Molnar <mingo at elte.hu>
---

diff --git a/kernel/sched_features.h b/kernel/sched_features.h
index 7c9e8f4..fda0162 100644
--- a/kernel/sched_features.h
+++ b/kernel/sched_features.h
@@ -5,7 +5,7 @@ SCHED_FEAT(START_DEBIT, 1)
 SCHED_FEAT(AFFINE_WAKEUPS, 1)
 SCHED_FEAT(CACHE_HOT_BUDDY, 1)
 SCHED_FEAT(SYNC_WAKEUPS, 1)
-SCHED_FEAT(HRTICK, 1)
+SCHED_FEAT(HRTICK, 0)
 SCHED_FEAT(DOUBLE_TICK, 0)
 SCHED_FEAT(ASYM_GRAN, 1)
 SCHED_FEAT(LB_BIAS, 1)


--- NEW FILE linux-2.6-sched_clock-prevent-scd-clock-from-moving-backwards ---
From: Dave Kleikamp <shaggy at linux.vnet.ibm.com>
Date: Thu, 9 Oct 2008 18:21:30 +0000 (-0500)
Subject: sched_clock: prevent scd->clock from moving backwards
X-Git-Tag: v2.6.28-rc1~43^2~10^2
X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftorvalds%2Flinux-2.6.git;a=commitdiff_plain;h=5b7dba4

sched_clock: prevent scd->clock from moving backwards

When sched_clock_cpu() couples the clocks between two cpus, it may
increment scd->clock beyond the GTOD tick window that __update_sched_clock()
uses to clamp the clock.  A later call to __update_sched_clock() may move
the clock back to scd->tick_gtod + TICK_NSEC, violating the clock's
monotonic property.

This patch ensures that scd->clock will not be set backward.

Signed-off-by: Dave Kleikamp <shaggy at linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra at chello.nl>
Signed-off-by: Ingo Molnar <mingo at elte.hu>
---

diff --git a/kernel/sched_clock.c b/kernel/sched_clock.c
index e8ab096..8178724 100644
--- a/kernel/sched_clock.c
+++ b/kernel/sched_clock.c
@@ -118,13 +118,13 @@ static u64 __update_sched_clock(struct sched_clock_data *scd, u64 now)
 
 	/*
 	 * scd->clock = clamp(scd->tick_gtod + delta,
-	 * 		      max(scd->tick_gtod, scd->clock),
-	 * 		      scd->tick_gtod + TICK_NSEC);
+	 *		      max(scd->tick_gtod, scd->clock),
+	 *		      max(scd->clock, scd->tick_gtod + TICK_NSEC));
 	 */
 
 	clock = scd->tick_gtod + delta;
 	min_clock = wrap_max(scd->tick_gtod, scd->clock);
-	max_clock = scd->tick_gtod + TICK_NSEC;
+	max_clock = wrap_max(scd->clock, scd->tick_gtod + TICK_NSEC);
 
 	clock = wrap_max(clock, min_clock);
 	clock = wrap_min(clock, max_clock);


Index: TODO
===================================================================
RCS file: /cvs/pkgs/rpms/kernel/devel/TODO,v
retrieving revision 1.29
retrieving revision 1.30
diff -u -r1.29 -r1.30
--- TODO	26 Oct 2008 00:04:17 -0000	1.29
+++ TODO	26 Oct 2008 05:04:32 -0000	1.30
@@ -184,3 +184,6 @@
 linux-2.6-net-tcp-option-ordering.patch
 	Backport of fd6149d332973bafa50f03ddb0ea9513e67f4517 from .28
 
+linux-2.6-sched-features-disable-hrtick.patch
+linux-2.6-sched_clock-prevent-scd-clock-from-moving-backwards
+	Scheduler patches from 2.6.28, should go to -stable


Index: kernel.spec
===================================================================
RCS file: /cvs/pkgs/rpms/kernel/devel/kernel.spec,v
retrieving revision 1.1084
retrieving revision 1.1085
diff -u -r1.1084 -r1.1085
--- kernel.spec	26 Oct 2008 00:04:18 -0000	1.1084
+++ kernel.spec	26 Oct 2008 05:04:32 -0000	1.1085
@@ -591,6 +591,9 @@
 Patch41: linux-2.6-sysrq-c.patch
 Patch44: linux-2.6-x86-avoid-dereferencing-beyond-stack-THREAD_SIZE.patch
 
+Patch60: linux-2.6-sched-features-disable-hrtick.patch
+Patch61: linux-2.6-sched_clock-prevent-scd-clock-from-moving-backwards
+
 Patch140: linux-2.6-ps3-ehci-iso.patch
 Patch141: linux-2.6-ps3-storage-alias.patch
 Patch142: linux-2.6-ps3-legacy-bootloader-hack.patch
@@ -1076,6 +1079,10 @@
 # enable sysrq-c on all kernels, not only kexec
 ApplyPatch linux-2.6-sysrq-c.patch
 
+# scheduler
+ApplyPatch linux-2.6-sched-features-disable-hrtick.patch
+ApplyPatch linux-2.6-sched_clock-prevent-scd-clock-from-moving-backwards
+
 # Architecture patches
 # x86(-64)
 # don't oops in get_wchan()
@@ -1860,6 +1867,11 @@
 %kernel_variant_files -k vmlinux %{with_kdump} kdump
 
 %changelog
+* Sat Oct 25 2008 Chuck Ebbert <cebbert at redhat.com> 2.6.27.4-49.rc3
+- Scheduler fixes from 2.6.28, fixing performance problems:
+    Disable HRTICK scheduler feature.
+    Keep the scheduler clock from going backwards.
+
 * Sat Oct 25 2008 Dave Jones <davej at redhat.com> 2.6.27.4-48.rc3
 - tcp: Restore ordering of TCP options for the sake of inter-operability