Matt Fleming a55c7454a8 sched/topology: Improve load balancing on AMD EPYC systems ... SD_BALANCE_{FORK,EXEC} and SD_WAKE_AFFINE are stripped in sd_init() for any sched domains with a NUMA distance greater than 2 hops (RECLAIM_DISTANCE). The idea being that it's expensive to balance across domains that far apart. However, as is rather unfortunately explained in: commit 32e45ff43e ("mm: increase RECLAIM_DISTANCE to 30") the value for RECLAIM_DISTANCE is based on node distance tables from 2011-era hardware. Current AMD EPYC machines have the following NUMA node distances: node distances: node 0 1 2 3 4 5 6 7 0: 10 16 16 16 32 32 32 32 1: 16 10 16 16 32 32 32 32 2: 16 16 10 16 32 32 32 32 3: 16 16 16 10 32 32 32 32 4: 32 32 32 32 10 16 16 16 5: 32 32 32 32 16 10 16 16 6: 32 32 32 32 16 16 10 16 7: 32 32 32 32 16 16 16 10 where 2 hops is 32. The result is that the scheduler fails to load balance properly across NUMA nodes on different sockets -- 2 hops apart. For example, pinning 16 busy threads to NUMA nodes 0 (CPUs 0-7) and 4 (CPUs 32-39) like so, $ numactl -C 0-7,32-39 ./spinner 16 causes all threads to fork and remain on node 0 until the active balancer kicks in after a few seconds and forcibly moves some threads to node 4. Override node_reclaim_distance for AMD Zen. Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Mel Gorman <mgorman@techsingularity.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Suravee.Suthikulpanit@amd.com Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Thomas.Lendacky@amd.com Cc: Tony Luck <tony.luck@intel.com> Link: https://lkml.kernel.org/r/20190808195301.13222-3-matt@codeblueprint.co.uk Signed-off-by: Ingo Molnar <mingo@kernel.org>		2019-09-03 09:17:37 +02:00
..
acpi
asm-generic	Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux	2019-07-17 13:13:41 -07:00
clocksource
crypto
drm	drm fixes for -rc1:	2019-07-19 12:29:43 -07:00
dt-bindings	ARM: Device-tree updates	2019-07-19 17:19:24 -07:00
keys
kvm
linux	sched/topology: Improve load balancing on AMD EPYC systems	2019-09-03 09:17:37 +02:00
math-emu
media
misc
net	tcp: be more careful in tcp_fragment()	2019-07-21 20:41:24 -07:00
pcmcia
ras
rdma
scsi	SCSI fixes on 20190720	2019-07-20 10:04:58 -07:00
soc	ARM: SoC-related driver updates	2019-07-19 17:13:56 -07:00
sound
target
trace	NFS client updates for Linux 5.3	2019-07-18 14:32:33 -07:00
uapi	media updates for v5.3-rc1	2019-07-22 09:01:47 -07:00
vdso
video
xen	xen: remove tmem driver	2019-07-17 08:09:58 +02:00
Kbuild	kbuild: add net/netfilter/nf_tables_offload.h to header-test blacklist.	2019-07-21 11:43:43 -07:00