linux

mirror of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2025-08-04 00:06:36 +00:00

No description

Find a file

Mel Gorman e496132ebe sched/fair: Adjust the allowed NUMA imbalance when SD_NUMA spans multiple LLCs Commit `7d2b5dd0bc` ("sched/numa: Allow a floating imbalance between NUMA nodes") allowed an imbalance between NUMA nodes such that communicating tasks would not be pulled apart by the load balancer. This works fine when there is a 1:1 relationship between LLC and node but can be suboptimal for multiple LLCs if independent tasks prematurely use CPUs sharing cache. Zen* has multiple LLCs per node with local memory channels and due to the allowed imbalance, it's far harder to tune some workloads to run optimally than it is on hardware that has 1 LLC per node. This patch allows an imbalance to exist up to the point where LLCs should be balanced between nodes. On a Zen3 machine running STREAM parallelised with OMP to have on instance per LLC the results and without binding, the results are 5.17.0-rc0 5.17.0-rc0 vanilla sched-numaimb-v6 MB/sec copy-16 162596.94 ( 0.00%) 580559.74 ( 257.05%) MB/sec scale-16 136901.28 ( 0.00%) 374450.52 ( 173.52%) MB/sec add-16 157300.70 ( 0.00%) 564113.76 ( 258.62%) MB/sec triad-16 151446.88 ( 0.00%) 564304.24 ( 272.61%) STREAM can use directives to force the spread if the OpenMP is new enough but that doesn't help if an application uses threads and it's not known in advance how many threads will be created. Coremark is a CPU and cache intensive benchmark parallelised with threads. When running with 1 thread per core, the vanilla kernel allows threads to contend on cache. With the patch; 5.17.0-rc0 5.17.0-rc0 vanilla sched-numaimb-v5 Min Score-16 368239.36 ( 0.00%) 389816.06 ( 5.86%) Hmean Score-16 388607.33 ( 0.00%) 427877.08 * 10.11%* Max Score-16 408945.69 ( 0.00%) 481022.17 ( 17.62%) Stddev Score-16 15247.04 ( 0.00%) 24966.82 ( -63.75%) CoeffVar Score-16 3.92 ( 0.00%) 5.82 ( -48.48%) It can also make a big difference for semi-realistic workloads like specjbb which can execute arbitrary numbers of threads without advance knowledge of how they should be placed. Even in cases where the average performance is neutral, the results are more stable. 5.17.0-rc0 5.17.0-rc0 vanilla sched-numaimb-v6 Hmean tput-1 71631.55 ( 0.00%) 73065.57 ( 2.00%) Hmean tput-8 582758.78 ( 0.00%) 556777.23 ( -4.46%) Hmean tput-16 1020372.75 ( 0.00%) 1009995.26 ( -1.02%) Hmean tput-24 1416430.67 ( 0.00%) 1398700.11 ( -1.25%) Hmean tput-32 1687702.72 ( 0.00%) 1671357.04 ( -0.97%) Hmean tput-40 1798094.90 ( 0.00%) 2015616.46 * 12.10%* Hmean tput-48 1972731.77 ( 0.00%) 2333233.72 ( 18.27%) Hmean tput-56 2386872.38 ( 0.00%) 2759483.38 ( 15.61%) Hmean tput-64 2909475.33 ( 0.00%) 2925074.69 ( 0.54%) Hmean tput-72 2585071.36 ( 0.00%) 2962443.97 ( 14.60%) Hmean tput-80 2994387.24 ( 0.00%) 3015980.59 ( 0.72%) Hmean tput-88 3061408.57 ( 0.00%) 3010296.16 ( -1.67%) Hmean tput-96 3052394.82 ( 0.00%) 2784743.41 ( -8.77%) Hmean tput-104 2997814.76 ( 0.00%) 2758184.50 ( -7.99%) Hmean tput-112 2955353.29 ( 0.00%) 2859705.09 ( -3.24%) Hmean tput-120 2889770.71 ( 0.00%) 2764478.46 ( -4.34%) Hmean tput-128 2871713.84 ( 0.00%) 2750136.73 ( -4.23%) Stddev tput-1 5325.93 ( 0.00%) 2002.53 ( 62.40%) Stddev tput-8 6630.54 ( 0.00%) 10905.00 ( -64.47%) Stddev tput-16 25608.58 ( 0.00%) 6851.16 ( 73.25%) Stddev tput-24 12117.69 ( 0.00%) 4227.79 ( 65.11%) Stddev tput-32 27577.16 ( 0.00%) 8761.05 ( 68.23%) Stddev tput-40 59505.86 ( 0.00%) 2048.49 ( 96.56%) Stddev tput-48 168330.30 ( 0.00%) 93058.08 ( 44.72%) Stddev tput-56 219540.39 ( 0.00%) 30687.02 ( 86.02%) Stddev tput-64 121750.35 ( 0.00%) 9617.36 ( 92.10%) Stddev tput-72 223387.05 ( 0.00%) 34081.13 ( 84.74%) Stddev tput-80 128198.46 ( 0.00%) 22565.19 ( 82.40%) Stddev tput-88 136665.36 ( 0.00%) 27905.97 ( 79.58%) Stddev tput-96 111925.81 ( 0.00%) 99615.79 ( 11.00%) Stddev tput-104 146455.96 ( 0.00%) 28861.98 ( 80.29%) Stddev tput-112 88740.49 ( 0.00%) 58288.23 ( 34.32%) Stddev tput-120 186384.86 ( 0.00%) 45812.03 ( 75.42%) Stddev tput-128 78761.09 ( 0.00%) 57418.48 ( 27.10%) Similarly, for embarassingly parallel problems like NPB-ep, there are improvements due to better spreading across LLC when the machine is not fully utilised. vanilla sched-numaimb-v6 Min ep.D 31.79 ( 0.00%) 26.11 ( 17.87%) Amean ep.D 31.86 ( 0.00%) 26.17 * 17.86%* Stddev ep.D 0.07 ( 0.00%) 0.05 ( 24.41%) CoeffVar ep.D 0.22 ( 0.00%) 0.20 ( 7.97%) Max ep.D 31.93 ( 0.00%) 26.21 ( 17.91%) Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com> Tested-by: K Prateek Nayak <kprateek.nayak@amd.com> Link: https://lore.kernel.org/r/20220208094334.16379-3-mgorman@techsingularity.net		2022-02-11 23:30:08 +01:00
arch	bitmap patches for 5.17-rc1	2022-01-23 06:20:44 +02:00
block	bitmap patches for 5.17-rc1	2022-01-23 06:20:44 +02:00
certs	certs: Fix build error when CONFIG_MODULE_SIG_KEY is empty	2022-01-23 00:08:44 +09:00
crypto	lib/crypto: add prompts back to crypto libraries	2022-01-18 13:03:55 +01:00
Documentation	Merge branch 'akpm' (patches from Andrew)	2022-01-22 11:28:23 +02:00
drivers	bitmap patches for 5.17-rc1	2022-01-23 06:20:44 +02:00
fs	bitmap patches for 5.17-rc1	2022-01-23 06:20:44 +02:00
include	sched/fair: Adjust the allowed NUMA imbalance when SD_NUMA spans multiple LLCs	2022-02-11 23:30:08 +01:00
init	lib/stackdepot: allow optional init and stack_table allocation by kvmalloc()	2022-01-22 08:33:37 +02:00
ipc	proc: remove PDE_DATA() completely	2022-01-22 08:33:37 +02:00
kernel	sched/fair: Adjust the allowed NUMA imbalance when SD_NUMA spans multiple LLCs	2022-02-11 23:30:08 +01:00
lib	bitmap patches for 5.17-rc1	2022-01-23 06:20:44 +02:00
LICENSES	LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers	2021-12-16 14:33:10 +01:00
mm	bitmap patches for 5.17-rc1	2022-01-23 06:20:44 +02:00
net	bitmap patches for 5.17-rc1	2022-01-23 06:20:44 +02:00
samples	Merge branch 'akpm' (patches from Andrew)	2022-01-20 10:41:01 +02:00
scripts	Devicetree fixes for v5.17, take 1:	2022-01-22 09:52:17 +02:00
security	fs.idmapped.v5.17	2022-01-11 14:26:55 -08:00
sound	proc: remove PDE_DATA() completely	2022-01-22 08:33:37 +02:00
tools	selftests/rseq: Change type of rseq_offset to ptrdiff_t	2022-02-11 23:30:08 +01:00
usr	usr/include/Makefile: add linux/nfc.h to the compile-test coverage	2022-01-22 21:48:45 +09:00
virt	Generic:	2022-01-22 09:40:01 +02:00
.clang-format	genirq/msi: Make interrupt allocation less convoluted	2021-12-16 22:22:20 +01:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore	.gitignore: ignore only top-level modules.builtin	2021-05-02 00:43:35 +09:00
.mailmap	RISCV:	2022-01-16 16:15:14 +02:00
COPYING
CREDITS	MAINTAINERS: Removing Ohad from remoteproc/rpmsg maintenance	2021-12-08 10:09:40 -07:00
Kbuild
Kconfig	kbuild: ensure full rebuild when the compiler is updated	2020-05-12 13:28:33 +09:00
MAINTAINERS	MAINTAINERS: add Suren as psi co-maintainer	2022-01-27 12:57:18 +01:00
Makefile	Linux 5.17-rc1	2022-01-23 10:12:53 +02:00
README

README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.