On Mon, 23 Feb 2015, riel@xxxxxxxxxx wrote:
> From: Rik van Riel <riel@xxxxxxxxxx>
>
> The previous patch makes it so the code skips over isolcpus when
> building scheduler load balancing domains. This makes it hard to
> see for a user which of the CPUs in a cpuset are participating in
> load balancing, and which ones are isolated cpus.
>
> Add a cpuset.isolcpus file with info on which cpus in a cpuset are
> isolated CPUs.
>
> This file is read-only for now. In the future we could extend things
> so isolcpus can be changed at run time, for the root (system wide)
> cpuset only.
>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Clark Williams <williams@xxxxxxxxxx>
> Cc: Li Zefan <lizefan@xxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: Luiz Capitulino <lcapitulino@xxxxxxxxxx>
> Cc: cgroups@xxxxxxxxxxxxxxx
> Signed-off-by: Rik van Riel <riel@xxxxxxxxxx>
> ---
> kernel/cpuset.c | 27 +++++++++++++++++++++++++++
> 1 file changed, 27 insertions(+)
>
> diff --git a/kernel/cpuset.c b/kernel/cpuset.c
> index 1ad63fa37cb4..19ad5d3377f8 100644
> --- a/kernel/cpuset.c
> +++ b/kernel/cpuset.c
> @@ -1563,6 +1563,7 @@ typedef enum {
> FILE_MEMORY_PRESSURE,
> FILE_SPREAD_PAGE,
> FILE_SPREAD_SLAB,
> + FILE_ISOLCPUS,
> } cpuset_filetype_t;
>
> static int cpuset_write_u64(struct cgroup_subsys_state *css, struct cftype *cft,
> @@ -1704,6 +1705,23 @@ static ssize_t cpuset_write_resmask(struct kernfs_open_file *of,
> return retval ?: nbytes;
> }
>
> +static size_t cpuset_sprintf_isolcpus(char *s, ssize_t pos, struct cpuset *cs)
> +{
> + cpumask_var_t my_isolated_cpus;
> + ssize_t count;
> +
Whitespace.
> + if (!alloc_cpumask_var(&my_isolated_cpus, GFP_KERNEL))
> + return 0;
> +
> + cpumask_and(my_isolated_cpus, cs->cpus_allowed, cpu_isolated_map);
> +
> + count = cpulist_scnprintf(s, pos, my_isolated_cpus);
> +
> + free_cpumask_var(my_isolated_cpus);
> +
> + return count;
> +}
> +
> /*
> * These ascii lists should be read in a single call, by using a user
> * buffer large enough to hold the entire map. If read in smaller
> @@ -1738,6 +1756,9 @@ static int cpuset_common_seq_show(struct seq_file *sf, void *v)
> case FILE_EFFECTIVE_MEMLIST:
> s += nodelist_scnprintf(s, count, cs->effective_mems);
> break;
> + case FILE_ISOLCPUS:
> + s += cpuset_sprintf_isolcpus(s, count, cs);
> + break;
This patch looks fine, and I think cpuset.effective_cpus and
cpuset.isolcpus can be used well together, but will need updating now that
commit e8e6d97c9b ("cpuset: use %*pb[l] to print bitmaps including
cpumasks and nodemasks") has been merged which reworks this function.
It's a little unfortunate, though, that the user sees Cpus_allowed,
cpuset.cpus, and cpuset.effective_cpus that include isolcpus and then have
to check another cpulist for the isolcpus to see their sched domain,
though.
> default:
> ret = -EINVAL;
> goto out_unlock;
> @@ -1906,6 +1927,12 @@ static struct cftype files[] = {
> .private = FILE_MEMORY_PRESSURE_ENABLED,
> },
>
> + {
> + .name = "isolcpus",
> + .seq_show = cpuset_common_seq_show,
> + .private = FILE_ISOLCPUS,
> + },
> +
> { } /* terminate */
> };
>
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