Messages in this thread | | | Subject | Re: [PATCH] arm64: Skip apply SSBS call for non SSBS system | From | Gaurav Kohli <> | Date | Wed, 12 Aug 2020 19:45:12 +0530 |
| |
On 8/12/2020 7:00 PM, Will Deacon wrote: > On Tue, Aug 04, 2020 at 07:44:42PM +0530, Gaurav Kohli wrote: >> In a system where no cpu's implement SSBS, for >> them no need to set pstate. This might help to save >> few cpu cycles during context switch. >> >> Signed-off-by: Gaurav Kohli <gkohli@codeaurora.org> >> >> diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c >> index 6089638..79f80f1 100644 >> --- a/arch/arm64/kernel/process.c >> +++ b/arch/arm64/kernel/process.c >> @@ -477,6 +477,13 @@ static void ssbs_thread_switch(struct task_struct *next) >> struct pt_regs *regs = task_pt_regs(next); >> >> /* >> + * For Targets which don't have SSBS support, they >> + * can return from here. >> + */ >> + if (!IS_ENABLED(CONFIG_ARM64_SSBD)) >> + return; > > Does this actually make a measurable difference? > > Will >
Hi Will,
While doing code review between older kernel and latest kernel for context switch case, there i have found this and thought it is good to have for non-ssbs system to return early(as this might improve).
Please let me know if you want to run some tests.
Regards Gaurav
| |