--- /dev/null
+From 6da3eced8c5f3b03340b0c395bacd552c4d52411 Mon Sep 17 00:00:00 2001
+From: "Jason A. Donenfeld" <Jason@zx2c4.com>
+Date: Mon, 23 Dec 2019 14:31:47 +0100
+Subject: powerpc/spinlocks: Include correct header for static key
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+From: Jason A. Donenfeld <Jason@zx2c4.com>
+
+commit 6da3eced8c5f3b03340b0c395bacd552c4d52411 upstream.
+
+Recently, the spinlock implementation grew a static key optimization,
+but the jump_label.h header include was left out, leading to build
+errors:
+
+ linux/arch/powerpc/include/asm/spinlock.h:44:7: error: implicit declaration of function ‘static_branch_unlikely’
+ 44 | if (!static_branch_unlikely(&shared_processor))
+
+This commit adds the missing header.
+
+mpe: The build break is only seen with CONFIG_JUMP_LABEL=n.
+
+Fixes: 656c21d6af5d ("powerpc/shared: Use static key to detect shared processor")
+Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
+Reviewed-by: Srikar Dronamraju <srikar@linux.ibm.com>
+Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
+Link: https://lore.kernel.org/r/20191223133147.129983-1-Jason@zx2c4.com
+Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ arch/powerpc/include/asm/spinlock.h | 1 +
+ 1 file changed, 1 insertion(+)
+
+--- a/arch/powerpc/include/asm/spinlock.h
++++ b/arch/powerpc/include/asm/spinlock.h
+@@ -15,6 +15,7 @@
+ *
+ * (the type definitions are in asm/spinlock_types.h)
+ */
++#include <linux/jump_label.h>
+ #include <linux/irqflags.h>
+ #ifdef CONFIG_PPC64
+ #include <asm/paca.h>
--- /dev/null
+From 14c73bd344da60abaf7da3ea2e7733ddda35bbac Mon Sep 17 00:00:00 2001
+From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
+Date: Thu, 5 Dec 2019 14:02:17 +0530
+Subject: powerpc/vcpu: Assume dedicated processors as non-preempt
+
+From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
+
+commit 14c73bd344da60abaf7da3ea2e7733ddda35bbac upstream.
+
+With commit 247f2f6f3c70 ("sched/core: Don't schedule threads on
+pre-empted vCPUs"), the scheduler avoids preempted vCPUs to schedule
+tasks on wakeup. This leads to wrong choice of CPU, which in-turn
+leads to larger wakeup latencies. Eventually, it leads to performance
+regression in latency sensitive benchmarks like soltp, schbench etc.
+
+On Powerpc, vcpu_is_preempted() only looks at yield_count. If the
+yield_count is odd, the vCPU is assumed to be preempted. However
+yield_count is increased whenever the LPAR enters CEDE state (idle).
+So any CPU that has entered CEDE state is assumed to be preempted.
+
+Even if vCPU of dedicated LPAR is preempted/donated, it should have
+right of first-use since they are supposed to own the vCPU.
+
+On a Power9 System with 32 cores:
+ # lscpu
+ Architecture: ppc64le
+ Byte Order: Little Endian
+ CPU(s): 128
+ On-line CPU(s) list: 0-127
+ Thread(s) per core: 8
+ Core(s) per socket: 1
+ Socket(s): 16
+ NUMA node(s): 2
+ Model: 2.2 (pvr 004e 0202)
+ Model name: POWER9 (architected), altivec supported
+ Hypervisor vendor: pHyp
+ Virtualization type: para
+ L1d cache: 32K
+ L1i cache: 32K
+ L2 cache: 512K
+ L3 cache: 10240K
+ NUMA node0 CPU(s): 0-63
+ NUMA node1 CPU(s): 64-127
+
+ # perf stat -a -r 5 ./schbench
+ v5.4 v5.4 + patch
+ Latency percentiles (usec) Latency percentiles (usec)
+ 50.0000th: 45 50.0th: 45
+ 75.0000th: 62 75.0th: 63
+ 90.0000th: 71 90.0th: 74
+ 95.0000th: 77 95.0th: 78
+ *99.0000th: 91 *99.0th: 82
+ 99.5000th: 707 99.5th: 83
+ 99.9000th: 6920 99.9th: 86
+ min=0, max=10048 min=0, max=96
+ Latency percentiles (usec) Latency percentiles (usec)
+ 50.0000th: 45 50.0th: 46
+ 75.0000th: 61 75.0th: 64
+ 90.0000th: 72 90.0th: 75
+ 95.0000th: 79 95.0th: 79
+ *99.0000th: 691 *99.0th: 83
+ 99.5000th: 3972 99.5th: 85
+ 99.9000th: 8368 99.9th: 91
+ min=0, max=16606 min=0, max=117
+ Latency percentiles (usec) Latency percentiles (usec)
+ 50.0000th: 45 50.0th: 46
+ 75.0000th: 61 75.0th: 64
+ 90.0000th: 71 90.0th: 75
+ 95.0000th: 77 95.0th: 79
+ *99.0000th: 106 *99.0th: 83
+ 99.5000th: 2364 99.5th: 84
+ 99.9000th: 7480 99.9th: 90
+ min=0, max=10001 min=0, max=95
+ Latency percentiles (usec) Latency percentiles (usec)
+ 50.0000th: 45 50.0th: 47
+ 75.0000th: 62 75.0th: 65
+ 90.0000th: 72 90.0th: 75
+ 95.0000th: 78 95.0th: 79
+ *99.0000th: 93 *99.0th: 84
+ 99.5000th: 108 99.5th: 85
+ 99.9000th: 6792 99.9th: 90
+ min=0, max=17681 min=0, max=117
+ Latency percentiles (usec) Latency percentiles (usec)
+ 50.0000th: 46 50.0th: 45
+ 75.0000th: 62 75.0th: 64
+ 90.0000th: 73 90.0th: 75
+ 95.0000th: 79 95.0th: 79
+ *99.0000th: 113 *99.0th: 82
+ 99.5000th: 2724 99.5th: 83
+ 99.9000th: 6184 99.9th: 93
+ min=0, max=9887 min=0, max=111
+
+ Performance counter stats for 'system wide' (5 runs):
+
+ context-switches 43,373 ( +- 0.40% ) 44,597 ( +- 0.55% )
+ cpu-migrations 1,211 ( +- 5.04% ) 220 ( +- 6.23% )
+ page-faults 15,983 ( +- 5.21% ) 15,360 ( +- 3.38% )
+
+Waiman Long suggested using static_keys.
+
+Fixes: 247f2f6f3c70 ("sched/core: Don't schedule threads on pre-empted vCPUs")
+Cc: stable@vger.kernel.org # v4.18+
+Reported-by: Parth Shah <parth@linux.ibm.com>
+Reported-by: Ihor Pasichnyk <Ihor.Pasichnyk@ibm.com>
+Tested-by: Juri Lelli <juri.lelli@redhat.com>
+Acked-by: Waiman Long <longman@redhat.com>
+Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
+Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
+Acked-by: Phil Auld <pauld@redhat.com>
+Reviewed-by: Vaidyanathan Srinivasan <svaidy@linux.ibm.com>
+Tested-by: Parth Shah <parth@linux.ibm.com>
+[mpe: Move the key and setting of the key to pseries/setup.c]
+Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
+Link: https://lore.kernel.org/r/20191213035036.6913-1-mpe@ellerman.id.au
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ arch/powerpc/include/asm/spinlock.h | 4 +++-
+ arch/powerpc/platforms/pseries/setup.c | 7 +++++++
+ 2 files changed, 10 insertions(+), 1 deletion(-)
+
+--- a/arch/powerpc/include/asm/spinlock.h
++++ b/arch/powerpc/include/asm/spinlock.h
+@@ -36,10 +36,12 @@
+ #endif
+
+ #ifdef CONFIG_PPC_PSERIES
++DECLARE_STATIC_KEY_FALSE(shared_processor);
++
+ #define vcpu_is_preempted vcpu_is_preempted
+ static inline bool vcpu_is_preempted(int cpu)
+ {
+- if (!firmware_has_feature(FW_FEATURE_SPLPAR))
++ if (!static_branch_unlikely(&shared_processor))
+ return false;
+ return !!(be32_to_cpu(lppaca_of(cpu).yield_count) & 1);
+ }
+--- a/arch/powerpc/platforms/pseries/setup.c
++++ b/arch/powerpc/platforms/pseries/setup.c
+@@ -74,6 +74,9 @@
+ #include "pseries.h"
+ #include "../../../../drivers/pci/pci.h"
+
++DEFINE_STATIC_KEY_FALSE(shared_processor);
++EXPORT_SYMBOL_GPL(shared_processor);
++
+ int CMO_PrPSP = -1;
+ int CMO_SecPSP = -1;
+ unsigned long CMO_PageSize = (ASM_CONST(1) << IOMMU_PAGE_SHIFT_4K);
+@@ -758,6 +761,10 @@ static void __init pSeries_setup_arch(vo
+
+ if (firmware_has_feature(FW_FEATURE_LPAR)) {
+ vpa_init(boot_cpuid);
++
++ if (lppaca_shared_proc(get_lppaca()))
++ static_branch_enable(&shared_processor);
++
+ ppc_md.power_save = pseries_lpar_idle;
+ ppc_md.enable_pmcs = pseries_lpar_enable_pmcs;
+ #ifdef CONFIG_PCI_IOV
projects / thirdparty / kernel / stable-queue.git / commitdiff
