Messages in this thread | | | From | Valentin Schneider <> | Subject | Re: [PATCH v2 4/9] sched/topology: Kill SD_LOAD_BALANCE | Date | Thu, 19 Mar 2020 12:06:07 +0000 |
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On Thu, Mar 19 2020, Dietmar Eggemann wrote: > On 11.03.20 19:15, Valentin Schneider wrote: >> That flag is set unconditionally in sd_init(), and no one checks for it >> anymore. Remove it. > > Why not merge 3/9 and 4/9 ? > > [...] > >> diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h >> index f341163fedc9..8de2f9744569 100644 >> --- a/include/linux/sched/topology.h >> +++ b/include/linux/sched/topology.h >> @@ -11,21 +11,20 @@ >> */ >> #ifdef CONFIG_SMP >> >> -#define SD_LOAD_BALANCE 0x0001 /* Do load balancing on this domain. */ >> -#define SD_BALANCE_NEWIDLE 0x0002 /* Balance when about to become idle */ > > [...] > >> -#define SD_OVERLAP 0x2000 /* sched_domains of this level overlap */ >> -#define SD_NUMA 0x4000 /* cross-node balancing */ >> +#define SD_BALANCE_NEWIDLE 0x0001 /* Balance when about to become idle */ > > IMHO, changing the values of the remaining SD flags will break lots of > userspace scripts. >
True, and that includes some of my own scripts. That's also part of why I have this 3/9 and 4/9 split: 4/9 is the externally visible part. If deemed necessary, we could keep the definition of SD_LOAD_BALANCE but kill all of its uses.
Alternatively, I was thinking that we could leverage [1] to make /proc/sys/kernel/sched_domain/cpu*/domain*/flags print e.g. comma-separated flag names rather than flag values. That way the userland scripts would no longer have to contain some {flag_value : flag_name} translation.
[1]: https://lkml.kernel.org/r/20200311183320.19186-1-valentin.schneider@arm.com
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