| Kconfig (851462444d421c223965b12b836bef63da61b57f) | Kconfig (91d1aa43d30505b0b825db8898ffc80a8eca96c7) |
|---|---|
| 1config ARCH 2 string 3 option env="ARCH" 4 5config KERNELVERSION 6 string 7 option env="KERNELVERSION" 8 --- 472 unchanged lines hidden (view full) --- 481endchoice 482 483config PREEMPT_RCU 484 def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU ) 485 help 486 This option enables preemptible-RCU code that is common between 487 the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations. 488 | 1config ARCH 2 string 3 option env="ARCH" 4 5config KERNELVERSION 6 string 7 option env="KERNELVERSION" 8 --- 472 unchanged lines hidden (view full) --- 481endchoice 482 483config PREEMPT_RCU 484 def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU ) 485 help 486 This option enables preemptible-RCU code that is common between 487 the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations. 488 |
| 489config CONTEXT_TRACKING 490 bool 491 |
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| 489config RCU_USER_QS 490 bool "Consider userspace as in RCU extended quiescent state" | 492config RCU_USER_QS 493 bool "Consider userspace as in RCU extended quiescent state" |
| 491 depends on HAVE_RCU_USER_QS && SMP | 494 depends on HAVE_CONTEXT_TRACKING && SMP 495 select CONTEXT_TRACKING |
| 492 help 493 This option sets hooks on kernel / userspace boundaries and 494 puts RCU in extended quiescent state when the CPU runs in 495 userspace. It means that when a CPU runs in userspace, it is 496 excluded from the global RCU state machine and thus doesn't | 496 help 497 This option sets hooks on kernel / userspace boundaries and 498 puts RCU in extended quiescent state when the CPU runs in 499 userspace. It means that when a CPU runs in userspace, it is 500 excluded from the global RCU state machine and thus doesn't |
| 497 to keep the timer tick on for RCU. | 501 try to keep the timer tick on for RCU. |
| 498 499 Unless you want to hack and help the development of the full | 502 503 Unless you want to hack and help the development of the full |
| 500 tickless feature, you shouldn't enable this option. It adds 501 unnecessary overhead. | 504 dynticks mode, you shouldn't enable this option. It also 505 adds unnecessary overhead. |
| 502 503 If unsure say N 504 | 506 507 If unsure say N 508 |
| 505config RCU_USER_QS_FORCE 506 bool "Force userspace extended QS by default" 507 depends on RCU_USER_QS | 509config CONTEXT_TRACKING_FORCE 510 bool "Force context tracking" 511 depends on CONTEXT_TRACKING |
| 508 help | 512 help |
| 509 Set the hooks in user/kernel boundaries by default in order to 510 test this feature that treats userspace as an extended quiescent 511 state until we have a real user like a full adaptive nohz option. | 513 Probe on user/kernel boundaries by default in order to 514 test the features that rely on it such as userspace RCU extended 515 quiescent states. 516 This test is there for debugging until we have a real user like the 517 full dynticks mode. |
| 512 | 518 |
| 513 Unless you want to hack and help the development of the full 514 tickless feature, you shouldn't enable this option. It adds 515 unnecessary overhead. 516 517 If unsure say N 518 | |
| 519config RCU_FANOUT 520 int "Tree-based hierarchical RCU fanout value" 521 range 2 64 if 64BIT 522 range 2 32 if !64BIT 523 depends on TREE_RCU || TREE_PREEMPT_RCU 524 default 64 if 64BIT 525 default 32 if !64BIT 526 help --- 50 unchanged lines hidden (view full) --- 577 578 Say N if unsure. 579 580config RCU_FAST_NO_HZ 581 bool "Accelerate last non-dyntick-idle CPU's grace periods" 582 depends on NO_HZ && SMP 583 default n 584 help | 519config RCU_FANOUT 520 int "Tree-based hierarchical RCU fanout value" 521 range 2 64 if 64BIT 522 range 2 32 if !64BIT 523 depends on TREE_RCU || TREE_PREEMPT_RCU 524 default 64 if 64BIT 525 default 32 if !64BIT 526 help --- 50 unchanged lines hidden (view full) --- 577 578 Say N if unsure. 579 580config RCU_FAST_NO_HZ 581 bool "Accelerate last non-dyntick-idle CPU's grace periods" 582 depends on NO_HZ && SMP 583 default n 584 help |
| 585 This option causes RCU to attempt to accelerate grace periods 586 in order to allow CPUs to enter dynticks-idle state more 587 quickly. On the other hand, this option increases the overhead 588 of the dynticks-idle checking, particularly on systems with 589 large numbers of CPUs. | 585 This option causes RCU to attempt to accelerate grace periods in 586 order to allow CPUs to enter dynticks-idle state more quickly. 587 On the other hand, this option increases the overhead of the 588 dynticks-idle checking, thus degrading scheduling latency. |
| 590 | 589 |
| 591 Say Y if energy efficiency is critically important, particularly 592 if you have relatively few CPUs. | 590 Say Y if energy efficiency is critically important, and you don't 591 care about real-time response. |
| 593 594 Say N if you are unsure. 595 596config TREE_RCU_TRACE 597 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU ) 598 select DEBUG_FS 599 help 600 This option provides tracing for the TREE_RCU and --- 49 unchanged lines hidden (view full) --- 650 help 651 This option specifies the time to wait after the beginning of 652 a given grace period before priority-boosting preempted RCU 653 readers blocking that grace period. Note that any RCU reader 654 blocking an expedited RCU grace period is boosted immediately. 655 656 Accept the default if unsure. 657 | 592 593 Say N if you are unsure. 594 595config TREE_RCU_TRACE 596 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU ) 597 select DEBUG_FS 598 help 599 This option provides tracing for the TREE_RCU and --- 49 unchanged lines hidden (view full) --- 649 help 650 This option specifies the time to wait after the beginning of 651 a given grace period before priority-boosting preempted RCU 652 readers blocking that grace period. Note that any RCU reader 653 blocking an expedited RCU grace period is boosted immediately. 654 655 Accept the default if unsure. 656 |
| 657config RCU_NOCB_CPU 658 bool "Offload RCU callback processing from boot-selected CPUs" 659 depends on TREE_RCU || TREE_PREEMPT_RCU 660 default n 661 help 662 Use this option to reduce OS jitter for aggressive HPC or 663 real-time workloads. It can also be used to offload RCU 664 callback invocation to energy-efficient CPUs in battery-powered 665 asymmetric multiprocessors. 666 667 This option offloads callback invocation from the set of 668 CPUs specified at boot time by the rcu_nocbs parameter. 669 For each such CPU, a kthread ("rcuoN") will be created to 670 invoke callbacks, where the "N" is the CPU being offloaded. 671 Nothing prevents this kthread from running on the specified 672 CPUs, but (1) the kthreads may be preempted between each 673 callback, and (2) affinity or cgroups can be used to force 674 the kthreads to run on whatever set of CPUs is desired. 675 676 Say Y here if you want reduced OS jitter on selected CPUs. 677 Say N here if you are unsure. 678 |
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| 658endmenu # "RCU Subsystem" 659 660config IKCONFIG 661 tristate "Kernel .config support" 662 ---help--- 663 This option enables the complete Linux kernel ".config" file 664 contents to be saved in the kernel. It provides documentation 665 of which kernel options are used in a running kernel or in an --- 1013 unchanged lines hidden --- | 679endmenu # "RCU Subsystem" 680 681config IKCONFIG 682 tristate "Kernel .config support" 683 ---help--- 684 This option enables the complete Linux kernel ".config" file 685 contents to be saved in the kernel. It provides documentation 686 of which kernel options are used in a running kernel or in an --- 1013 unchanged lines hidden --- |