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1f91e7a4 GKH |
1 | From foo@baz Tue 14 May 2019 08:29:35 PM CEST |
2 | From: Thomas Gleixner <tglx@linutronix.de> | |
3 | Date: Sun, 25 Nov 2018 19:33:37 +0100 | |
4 | Subject: x86/Kconfig: Select SCHED_SMT if SMP enabled | |
5 | ||
6 | From: Thomas Gleixner <tglx@linutronix.de> | |
7 | ||
8 | commit dbe733642e01dd108f71436aaea7b328cb28fd87 upstream. | |
9 | ||
10 | CONFIG_SCHED_SMT is enabled by all distros, so there is not a real point to | |
11 | have it configurable. The runtime overhead in the core scheduler code is | |
12 | minimal because the actual SMT scheduling parts are conditional on a static | |
13 | key. | |
14 | ||
15 | This allows to expose the scheduler's SMT state static key to the | |
16 | speculation control code. Alternatively the scheduler's static key could be | |
17 | made always available when CONFIG_SMP is enabled, but that's just adding an | |
18 | unused static key to every other architecture for nothing. | |
19 | ||
20 | Signed-off-by: Thomas Gleixner <tglx@linutronix.de> | |
21 | Reviewed-by: Ingo Molnar <mingo@kernel.org> | |
22 | Cc: Peter Zijlstra <peterz@infradead.org> | |
23 | Cc: Andy Lutomirski <luto@kernel.org> | |
24 | Cc: Linus Torvalds <torvalds@linux-foundation.org> | |
25 | Cc: Jiri Kosina <jkosina@suse.cz> | |
26 | Cc: Tom Lendacky <thomas.lendacky@amd.com> | |
27 | Cc: Josh Poimboeuf <jpoimboe@redhat.com> | |
28 | Cc: Andrea Arcangeli <aarcange@redhat.com> | |
29 | Cc: David Woodhouse <dwmw@amazon.co.uk> | |
30 | Cc: Tim Chen <tim.c.chen@linux.intel.com> | |
31 | Cc: Andi Kleen <ak@linux.intel.com> | |
32 | Cc: Dave Hansen <dave.hansen@intel.com> | |
33 | Cc: Casey Schaufler <casey.schaufler@intel.com> | |
34 | Cc: Asit Mallick <asit.k.mallick@intel.com> | |
35 | Cc: Arjan van de Ven <arjan@linux.intel.com> | |
36 | Cc: Jon Masters <jcm@redhat.com> | |
37 | Cc: Waiman Long <longman9394@gmail.com> | |
38 | Cc: Greg KH <gregkh@linuxfoundation.org> | |
39 | Cc: Dave Stewart <david.c.stewart@intel.com> | |
40 | Cc: Kees Cook <keescook@chromium.org> | |
41 | Link: https://lkml.kernel.org/r/20181125185004.337452245@linutronix.de | |
42 | Signed-off-by: Ben Hutchings <ben@decadent.org.uk> | |
43 | Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> | |
44 | --- | |
45 | arch/x86/Kconfig | 8 +------- | |
46 | 1 file changed, 1 insertion(+), 7 deletions(-) | |
47 | ||
48 | --- a/arch/x86/Kconfig | |
49 | +++ b/arch/x86/Kconfig | |
50 | @@ -893,13 +893,7 @@ config NR_CPUS | |
51 | approximately eight kilobytes to the kernel image. | |
52 | ||
53 | config SCHED_SMT | |
54 | - bool "SMT (Hyperthreading) scheduler support" | |
55 | - depends on SMP | |
56 | - ---help--- | |
57 | - SMT scheduler support improves the CPU scheduler's decision making | |
58 | - when dealing with Intel Pentium 4 chips with HyperThreading at a | |
59 | - cost of slightly increased overhead in some places. If unsure say | |
60 | - N here. | |
61 | + def_bool y if SMP | |
62 | ||
63 | config SCHED_MC | |
64 | def_bool y |