On Fri, 2018-05-11 at 16:47 +0530, Gautham R. Shenoy wrote:
> From: "Gautham R. Shenoy" <e...@linux.vnet.ibm.com>
>
> Each of the SMT4 cores forming a fused-core are more or less
> independent units. Thus when multiple tasks are scheduled to run on
> the fused core, we get the best performance when the tasks are spread
> across the pair of SMT4 cores.
>
> Since the threads in the pair of SMT4 cores of an interleaved big-core
> are numbered {0,2,4,6} and {1,3,5,7} respectively, enable ASYM_SMT on
> such interleaved big-cores that will bias the load-balancing of tasks
> on smaller numbered threads, which will automatically result in
> spreading the tasks uniformly across the associated pair of SMT4
> cores.
>
> Signed-off-by: Gautham R. Shenoy <e...@linux.vnet.ibm.com>
> ---
> arch/powerpc/kernel/smp.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
> index 9ca7148..0153f01 100644
> --- a/arch/powerpc/kernel/smp.c
> +++ b/arch/powerpc/kernel/smp.c
> @@ -1082,7 +1082,7 @@ static int powerpc_smt_flags(void)
> {
> int flags = SD_SHARE_CPUCAPACITY | SD_SHARE_PKG_RESOURCES;
>
> - if (cpu_has_feature(CPU_FTR_ASYM_SMT)) {
> + if (cpu_has_feature(CPU_FTR_ASYM_SMT) || has_interleaved_big_core) {
Shouldn't we just set CPU_FTR_ASYM_SMT and leave this code unchanged?
> printk_once(KERN_INFO "Enabling Asymmetric SMT
> scheduling\n");
> flags |= SD_ASYM_PACKING;
> }
