[PATCH 0/7] Optimization to improve cpu online/offline on Powerpc
Srikar Dronamraju
srikar at linux.vnet.ibm.com
Mon Jul 27 17:55:25 AEST 2020
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.
Here are some optimizations and fixes to make ppc64_cpu --smt=8/ppc64_cpu
--smt=1 run faster and hence boot the kernel also faster.
Its based on top of my v4 coregroup support patchset.
http://lore.kernel.org/lkml/20200727053230.19753-1-srikar@linux.vnet.ibm.com/t/#u
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 simple cleanups/optimizations.
Since cpu_core_mask is an exported symbol for a long duration, lets retain
as a snapshot of cpumask_of_node.
Architecture: ppc64le
Byte Order: Little Endian
CPU(s): 160
On-line CPU(s) list: 0-159
Thread(s) per core: 4
Core(s) per socket: 20
Socket(s): 2
NUMA node(s): 2
Model: 2.2 (pvr 004e 1202)
Model name: POWER9, altivec supported
CPU max MHz: 3800.0000
CPU min MHz: 2166.0000
L1d cache: 32K
L1i cache: 32K
L2 cache: 512K
L3 cache: 10240K
NUMA node0 CPU(s): 0-79
NUMA node8 CPU(s): 80-159
without patch (powerpc/next)
[ 0.099347] smp: Bringing up secondary CPUs ...
[ 0.832513] smp: Brought up 2 nodes, 160 CPUs
with powerpc/next + coregroup support patchset
[ 0.099241] smp: Bringing up secondary CPUs ...
[ 0.835627] smp: Brought up 2 nodes, 160 CPUs
with powerpc/next + coregroup + this patchset
[ 0.097232] smp: Bringing up secondary CPUs ...
[ 0.528457] smp: Brought up 2 nodes, 160 CPUs
x ppc64_cpu --smt=1
+ ppc64_cpu --smt=4
without patch
N Min Max Median Avg Stddev
x 100 11.82 17.06 14.01 14.05 1.2665247
+ 100 12.25 16.59 13.86 14.1143 1.164293
with patch
N Min Max Median Avg Stddev
x 100 12.68 16.15 14.24 14.238 0.75489246
+ 100 12.93 15.85 14.35 14.2897 0.60041813
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>
Srikar Dronamraju (7):
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
arch/powerpc/include/asm/smp.h | 5 --
arch/powerpc/include/asm/topology.h | 7 +--
arch/powerpc/kernel/smp.c | 79 +++++++++--------------------
3 files changed, 24 insertions(+), 67 deletions(-)
--
2.17.1
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