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SubjectRe: [PATCH v2] sched/debug: Put sched/domains files under the verbose flag
On Fri, Jan 20, 2023 at 11:33:30AM -0500, Phil Auld wrote:
> The debug files under sched/domains can take a long time to regenerate,
> especially when updates are done one at a time. Move these files under
> the sched verbose debug flag. Allow changes to verbose to trigger
> generation of the files. This lets a user batch the updates but still
> have the information available. The detailed topology printk messages
> are also under verbose.
>
> Discussion that lead to this approach can be found in the link below.
>
> Simplified code to maintain use of debugfs bool routines suggested by
> Michael Ellerman <mpe@ellerman.id.au>.
>
> Signed-off-by: Phil Auld <pauld@redhat.com>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> Cc: Valentin Schneider <vschneid@redhat.com>
> Cc: Vishal Chourasia <vishalc@linux.vnet.ibm.com>
> Cc: Vincent Guittot <vincent.guittot@linaro.org>
> Link: https://lore.kernel.org/all/Y01UWQL2y2r69sBX@li-05afa54c-330e-11b2-a85c-e3f3aa0db1e9.ibm.com/
> ---
>
> v2: fix comment typo and use cpumask_empty()
>
> kernel/sched/debug.c | 52 +++++++++++++++++++++++++++++++++++++++++---
> 1 file changed, 49 insertions(+), 3 deletions(-)

Thanks for the Patch.

Tested-by: Vishal Chourasia <vishalc@linux.vnet.ibm.com>

Base Tag : v6.2-rc8
Patch : [V2] sched/debug: Put sched/domains files under the verbose flag


# time ppc64_cpu --smt=off | When kernel is built
| with the patch, time to
real 17m54.246s | smt=off is 17m54s.
user 0m0.013s |
sys 0m4.661s |

System Configuration:

Architecture : ppc64le
CPUS : 1600
Machine : Power10
Thread per core : 8
Sockets : 15

- debug files are not created for the case where kernel command line string
lacks sched_verbose parameter.
- When sched_verbose is passed as kernel commandline parameter, kernel exports
/sys/kernel/debug/sched/verbose file which controls creation of the debug
files.
+ setting Y/N to this file enables/disables creation of debug files during CPU
hotplug operation.

Below is the table listing time taken to perform smt=off operation under
different settings.

+--------------------------+---------------+---------+------------+
| kernel | sched_verbose | verbose | time |
+--------------------------+---------------+---------+------------+
| 6.2.0-rc8-patch-applied+ | YES | N | 16m58.196s |
| 6.2.0-rc8-patch-applied+ | YES | Y | 33m21.774s |
| 6.2.0-rc8-patch-applied+ | NO | NA | 17m54.246s |
| 6.2.0-rc8 | NO | NA | 30m11.344s |
+--------------------------+---------------+---------+------------+

-- vishal.c[unhandled content-type:application/pgp-signature]
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