Tejun Heo 61debc251c sched_ext: Use per-CPU DSQs instead of per-node global DSQs in bypass mode ... Bypass mode routes tasks through fallback dispatch queues. Originally a single global DSQ, b7b3b2dbae ("sched_ext: Split the global DSQ per NUMA node") changed this to per-node DSQs to resolve NUMA-related livelocks. Dan Schatzberg found per-node DSQs can still livelock when many threads are pinned to different small CPU subsets: each CPU must scan many incompatible tasks to find runnable ones, causing severe contention with high CPU counts. Switch to per-CPU bypass DSQs. Each task queues on its current CPU. Default idle CPU selection and direct dispatch handle most cases well. This introduces a failure mode when tasks concentrate on one CPU in over-saturated systems. If the BPF scheduler severely skews placement before triggering bypass, that CPU's queue may be too long to drain, causing RCU stalls. A load balancer in a future patch will address this. The bypass DSQ is separate from local DSQ to enable load balancing: local DSQs use rq locks, preventing efficient scanning and transfer across CPUs, especially problematic when systems are already contended. v2: Clarified why bypass DSQ is separate from local DSQ (Andrea Righi). Reported-by: Dan Schatzberg <schatzberg.dan@gmail.com> Reviewed-by: Dan Schatzberg <schatzberg.dan@gmail.com> Reviewed-by: Andrea Righi <arighi@nvidia.com> Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com> Signed-off-by: Tejun Heo <tj@kernel.org>		2025-11-12 06:43:44 -10:00
..
acpi	More power management updates for 6.18-rc1	2025-10-07 09:39:51 -07:00
asm-generic	hyperv-next for v6.18	2025-10-07 08:40:15 -07:00
clocksource	clocksource/drivers/arm_arch_timer_mmio: Switch over to standalone driver	2025-09-23 12:31:50 +02:00
crypto	This update includes the following changes:	2025-10-04 14:59:29 -07:00
cxl
drm	drm/gpuvm: Fix kernel-doc warning for drm_gpuvm_map_req.map	2025-10-15 18:37:05 +02:00
dt-bindings	There's a bunch of patches here across drivers/clk/ to migrate drivers to use	2025-10-07 09:28:37 -07:00
hyperv	hyperv: Remove the spurious null directive line	2025-10-02 21:21:24 +00:00
keys	KEYS: trusted_tpm1: Move private functionality out of public header	2025-09-27 21:05:06 +03:00
kunit	linux_kselftest-kunit-6.18-rc1	2025-10-01 19:15:11 -07:00
kvm	KVM: arm64: Kill leftovers of ad-hoc timer userspace access	2025-10-13 14:42:41 +01:00
linux	sched_ext: Use per-CPU DSQs instead of per-node global DSQs in bypass mode	2025-11-12 06:43:44 -10:00
math-emu
media	media: v4l2-common: Add legacy camera sensor clock helper	2025-09-09 15:59:19 +02:00
memory
misc
net	net/ip6_tunnel: Prevent perpetual tunnel growth	2025-10-13 17:43:46 -07:00
pcmcia
ras
rdma
rv	kernel-6.18-rc1.clone3	2025-09-29 10:36:50 -07:00
scsi	SCSI misc on 20251002	2025-10-03 19:17:48 -07:00
soc	There's a bunch of patches here across drivers/clk/ to migrate drivers to use	2025-10-07 09:28:37 -07:00
sound	ASoC: tas2781: Support more newly-released amplifiers tas58xx in the driver	2025-10-13 11:08:09 +01:00
target
trace	dma-mapping fixes for Linux 6.18:	2025-10-07 12:48:06 -07:00
uapi	ARM:	2025-10-18 07:07:14 -10:00
ufs	scsi: ufs: core: Include UTP error in INT_FATAL_ERRORS	2025-09-30 16:10:29 -04:00
vdso	Updates for the VDSO subsystem:	2025-09-30 16:58:21 -07:00
video
xen	xen: replace XENFEAT_auto_translated_physmap with xen_pv_domain()	2025-09-08 17:01:36 +02:00
Kbuild