On Mon, Jul 27, 2020 at 01:25:25PM +0530, Srikar Dronamraju wrote:
> 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-sri...@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.
boot tested on P9 KVM guest.
without this series:
# dmesg|grep smp
[0.066624] smp: Bringing up secondary CPUs ...
[ 347.521264] smp: Brought up 1 node, 2048 CPUs
with this series:
# dmesg|grep smp
[0.067744] smp: Bringing up secondary CPUs ...
[5.416910] smp: Brought up 1 node, 2048 CPUs
Tested-by: Satheesh Rajendran
Regards,
-Satheesh
>
> 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.
> CPU min MHz: 2166.
> 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 MaxMedian AvgStddev
> 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 MaxMedian AvgStddev
> x 100 12.68 16.15 14.2414.2380.75489246
> + 100 12.93 15.85 14.35 14.28970.60041813
>
> Cc: linuxppc-dev
> Cc: LKML
> Cc: Michael Ellerman
> Cc: Nicholas Piggin
> Cc: Anton Blanchard
> Cc: Oliver O'Halloran
> Cc: Nathan Lynch
> Cc: Michael Neuling
> Cc: Gautham R Shenoy
> Cc: Satheesh Rajendran
> Cc: Ingo Molnar
> Cc: Peter Zijlstra
> Cc: Valentin Schneider
>
> 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
>
