[PATCH v2 00/11] Optimization to improve CPU online/offline on Powerpc
Srikar Dronamraju
srikar at linux.vnet.ibm.com
Mon Sep 21 19:56:42 AEST 2020
Here are some optimizations and fixes to make CPU online/offline
faster and hence result in faster bootup.
Its based on top of my v5 coregroup support patchset.
https://lore.kernel.org/linuxppc-dev/20200810071834.92514-1-srikar@linux.vnet.ibm.com/t/#u
Anton reported that his 4096 cpu (1024 cores in a socket) was taking too
long to boot. He also analyzed that most of the time was being spent on
updating cpu_core_mask.
The first two patches should solve Anton's immediate problem.
On the unofficial patches, Anton reported that the boot time came from 30
mins to 6 seconds. (Basically a high core count in a single socket
configuration). Satheesh also reported similar numbers.
The rest are cleanups/optimizations.
Since cpu_core_mask is an exported symbol for a long duration, lets retain
as a snapshot of cpumask_of_node.
$ lscpu
Architecture: ppc64le
Byte Order: Little Endian
CPU(s): 1024
On-line CPU(s) list: 0-1023
Thread(s) per core: 8
Core(s) per socket: 8
Socket(s): 16
NUMA node(s): 16
Model: 2.0 (pvr 004d 0200)
Model name: POWER8 (architected), altivec supported
Hypervisor vendor: pHyp
Virtualization type: para
L1d cache: 64K
L1i cache: 32K
L2 cache: 512K
L3 cache: 8192K
NUMA node0 CPU(s): 0-63
NUMA node1 CPU(s): 64-127
NUMA node2 CPU(s): 128-191
NUMA node3 CPU(s): 192-255
NUMA node4 CPU(s): 256-319
NUMA node5 CPU(s): 320-383
NUMA node6 CPU(s): 384-447
NUMA node7 CPU(s): 448-511
NUMA node8 CPU(s): 512-575
NUMA node9 CPU(s): 576-639
NUMA node10 CPU(s): 640-703
NUMA node11 CPU(s): 704-767
NUMA node12 CPU(s): 768-831
NUMA node13 CPU(s): 832-895
NUMA node14 CPU(s): 896-959
NUMA node15 CPU(s): 960-1023
$ dmesg -k | grep -i -e Bringing -e Brought -e sysrq -e bug
With powerp/next
[ 0.000000] printk: debug: ignoring loglevel setting.
[ 0.354971] smp: Bringing up secondary CPUs ...
[ 233.354676] smp: Brought up 16 nodes, 1024 CPUs
[ 330.023073] sysrq: Changing Loglevel
[ 330.023101] sysrq: Loglevel set to 9
With +patchset
[ 0.000000] printk: debug: ignoring loglevel setting.
[ 0.351703] smp: Bringing up secondary CPUs ...
[ 4.059859] smp: Brought up 16 nodes, 1024 CPUs
[ 98.309015] sysrq: Changing Loglevel
[ 98.309044] sysrq: Loglevel set to 9
Observations:
CPU bringup time reduced to 4 seconds from 233 seconds on this 1024 CPU
system. This resulted in System boot up time reducing to 98 seconds from
330 seconds. The actual improvement would depend on your system topology.
Topology verification post patchset on a 2 node Power9 PowerVM LPAR
powerpc/next +patchset
------------ ---------
$ lscpu
Architecture: ppc64le Architecture: ppc64le
Byte Order: Little Endian Byte Order: Little Endian
CPU(s): 128 CPU(s): 128
On-line CPU(s) list: 0-127 On-line CPU(s) list: 0-127
Thread(s) per core: 8 Thread(s) per core: 8
Core(s) per socket: 8 Core(s) per socket: 8
Socket(s): 2 Socket(s): 2
NUMA node(s): 2 NUMA node(s): 2
Model: 2.2 (pvr 004e 0202) Model: 2.2 (pvr 004e 0202)
Model name: POWER9 (architected), altivec supported Model name: POWER9 (architected), altivec supported
Hypervisor vendor: pHyp Hypervisor vendor: pHyp
Virtualization type: para Virtualization type: para
L1d cache: 32K L1d cache: 32K
L1i cache: 32K L1i cache: 32K
L2 cache: 512K L2 cache: 512K
L3 cache: 10240K L3 cache: 10240K
NUMA node0 CPU(s): 0-63 NUMA node0 CPU(s): 0-63
NUMA node1 CPU(s): 64-127 NUMA node1 CPU(s): 64-127
$ tail -f /proc/cpuinfo
processor : 127 processor : 127
cpu : POWER9 (architected), altivec supported cpu : POWER9 (architected), altivec supported
clock : 3000.000000MHz clock : 3000.000000MHz
revision : 2.2 (pvr 004e 0202) revision : 2.2 (pvr 004e 0202)
timebase : 512000000 timebase : 512000000
platform : pSeries platform : pSeries
model : IBM,9008-22L model : IBM,9008-22L
machine : CHRP IBM,9008-22L machine : CHRP IBM,9008-22L
MMU : Radix MMU : Radix
$ grep . /proc/sys/kernel/sched_domain/cpu0/domain*/name
--------------------------------------------------------
/proc/sys/kernel/sched_domain/cpu0/domain0/name:SMT /proc/sys/kernel/sched_domain/cpu0/domain0/name:SMT
/proc/sys/kernel/sched_domain/cpu0/domain1/name:CACHE /proc/sys/kernel/sched_domain/cpu0/domain1/name:CACHE
/proc/sys/kernel/sched_domain/cpu0/domain2/name:DIE /proc/sys/kernel/sched_domain/cpu0/domain2/name:DIE
/proc/sys/kernel/sched_domain/cpu0/domain3/name:NUMA /proc/sys/kernel/sched_domain/cpu0/domain3/name:NUMA
$ grep . /proc/sys/kernel/sched_domain/cpu0/domain*/flags
---------------------------------------------------------
/proc/sys/kernel/sched_domain/cpu0/domain0/flags:2391 /proc/sys/kernel/sched_domain/cpu0/domain0/flags:2391
/proc/sys/kernel/sched_domain/cpu0/domain1/flags:2327 /proc/sys/kernel/sched_domain/cpu0/domain1/flags:2327
/proc/sys/kernel/sched_domain/cpu0/domain2/flags:2071 /proc/sys/kernel/sched_domain/cpu0/domain2/flags:2071
/proc/sys/kernel/sched_domain/cpu0/domain3/flags:12801 /proc/sys/kernel/sched_domain/cpu0/domain3/flags:12801
Post ppc64_cpu --smt=1
$ tail -f /proc/cpuinfo
processor : 120 processor : 120
cpu : POWER9 (architected), altivec supported cpu : POWER9 (architected), altivec supported
clock : 3000.000000MHz clock : 3000.000000MHz
revision : 2.2 (pvr 004e 0202) revision : 2.2 (pvr 004e 0202)
timebase : 512000000 timebase : 512000000
platform : pSeries platform : pSeries
model : IBM,9008-22L model : IBM,9008-22L
machine : CHRP IBM,9008-22L machine : CHRP IBM,9008-22L
MMU : Radix MMU : Radix
$ grep . /proc/sys/kernel/sched_domain/cpu0/domain*/name
--------------------------------------------------------
/proc/sys/kernel/sched_domain/cpu0/domain0/name:DIE /proc/sys/kernel/sched_domain/cpu0/domain0/name:DIE
/proc/sys/kernel/sched_domain/cpu0/domain1/name:NUMA /proc/sys/kernel/sched_domain/cpu0/domain1/name:NUMA
$ grep . /proc/sys/kernel/sched_domain/cpu0/domain*/flags
---------------------------------------------------------
/proc/sys/kernel/sched_domain/cpu0/domain0/flags:2071 /proc/sys/kernel/sched_domain/cpu0/domain0/flags:2071
/proc/sys/kernel/sched_domain/cpu0/domain1/flags:12801 /proc/sys/kernel/sched_domain/cpu0/domain1/flags:12801
Performance impact post +patchset
---------------------------------
100 iterations of ebizzy
Units: Records/second : higher is better
-----------------------------------------
kernel N Min Max Median Avg Stddev
powerpc/next 100 753917 870520 819054 817636.56 22649.7
+patchset 100 746258 874984 816681 813876.74 26424.351
100 iterations of perf bench sched pipe -l 10000000 (aka Hackbench)
units: usec/ops: lesser is better
--------------------------------
kernel N Min Max Median Avg Stddev
powerpc/next 100 13.845834 14.569539 14.06263 14.086167 0.17512607
+patchset 100 13.637611 18.097744 13.862656 13.9257 0.43872453
schbench Latency percentiles (usec)
units: usec : lesser is better
-----------------------------------
powerpc/next +patchset
50.0000th: 48 50.0000th: 49
75.0000th: 65 75.0000th: 66
90.0000th: 77 90.0000th: 79
95.0000th: 84 95.0000th: 85
*99.0000th: 101 *99.0000th: 99
99.5000th: 113 99.5000th: 104
99.9000th: 159 99.9000th: 129
min=0, max=15221 min=0, max=7666
100 interations of ppc64_cpu --smt=1 / ppc64_cpu --smt=8
Units: seconds : lesser is better
---------------------------------
ppc64_cpu --smt=1
kernel N Min Max Median Avg Stddev
powerpc/next 100 13.39 17.55 14.71 14.7658 0.69184745
+patchset 100 13.3 16.27 14.33 14.4179 0.5427433
ppc64_cpu --smt=8
kernel N Min Max Median Avg Stddev
powerpc/next 100 21.65 26.17 23.71 23.7111 0.8589786
+patchset 100 21.88 25.79 23.16 23.2945 0.86394839
Observations:
Performance of ebizzy/ perf_sched_bench / schbench remain the
same with and without the patchset.
Cc: linuxppc-dev <linuxppc-dev at lists.ozlabs.org>
Cc: LKML <linux-kernel at vger.kernel.org>
Cc: Michael Ellerman <mpe at ellerman.id.au>
Cc: Nicholas Piggin <npiggin at gmail.com>
Cc: Anton Blanchard <anton at ozlabs.org>
Cc: Oliver O'Halloran <oohall at gmail.com>
Cc: Nathan Lynch <nathanl at linux.ibm.com>
Cc: Michael Neuling <mikey at neuling.org>
Cc: Gautham R Shenoy <ego at linux.vnet.ibm.com>
Cc: Satheesh Rajendran <sathnaga at linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo at kernel.org>
Cc: Peter Zijlstra <peterz at infradead.org>
Cc: Valentin Schneider <valentin.schneider at arm.com>
Signed-off-by: Srikar Dronamraju <srikar at linux.vnet.ibm.com>
Changelog v1->v2:
v1 link: https://lore.kernel.org/linuxppc-dev/20200727075532.30058-1-srikar@linux.vnet.ibm.com/t/#u
Added five more patches on top of Seven.
Rebased to 19th Sept 2020 powerpc/next (based on v5.9-rc2)
Srikar Dronamraju (11):
powerpc/topology: Update topology_core_cpumask
powerpc/smp: Stop updating cpu_core_mask
powerpc/smp: Remove get_physical_package_id
powerpc/smp: Optimize remove_cpu_from_masks
powerpc/smp: Limit CPUs traversed to within a node.
powerpc/smp: Stop passing mask to update_mask_by_l2
powerpc/smp: Depend on cpu_l1_cache_map when adding CPUs
powerpc/smp: Check for duplicate topologies and consolidate
powerpc/smp: Optimize update_mask_by_l2
powerpc/smp: Move coregroup mask updation to a new function
powerpc/smp: Optimize update_coregroup_mask
arch/powerpc/include/asm/smp.h | 5 -
arch/powerpc/include/asm/topology.h | 7 +-
arch/powerpc/kernel/smp.c | 186 ++++++++++++++++++----------
3 files changed, 120 insertions(+), 78 deletions(-)
--
2.17.1
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