On Wed, Apr 5, 2023 at 6:23 PM Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
On Wed, Apr 05, 2023 at 06:01:07PM +0700, Shaun Tancheff wrote:
> From: Shaun Tancheff <shaun.tancheff@xxxxxxx>
>
> For users that are unable to update to memcg-v2 this
> provides a method where memcg-v1 can more effectively
> apply enough memory pressure to effectively throttle
> filesystem I/O or otherwise minimize being memcg oom
> killed at the expense of reduced performance.
>
> This patch extends the memcg-v1 legacy sysfs entries
> with:
> limit_in_bytes.min, limit_in_bytes.low and
> limit_in_bytes.high
> Since old software will need to be updated to take
> advantage of the new files a secondary method
> of setting min, low and high based on a percentage
> of the limit is also provided. The percentages
> are determined by module parameters.
>
> The available module parameters can be set at
> kernel boot time, for example:
> memcontrol.memcg_min=10
> memcontrol.memcg_low=30
> memcontrol.memcg_high=80
>
> Would set min to 10%, low to 30% and high to 80% of
> the value written to:
> /sys/fs/cgroup/memory/<grp>/memory.limit_in_bytes
>
> Signed-off-by: Shaun Tancheff <shaun.tancheff@xxxxxxx>
> ---
> v0: Initial hard coded limits by percent.
> v1: Added sysfs access and module parameters for percent values to enable
> v2: Fix 32-bit, remove need for missing __udivdi3
> mm/memcontrol.c | 83 ++++++++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 82 insertions(+), 1 deletion(-)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 2eee092f8f11..3cf8386f4f45 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -73,6 +73,18 @@
>
> #include <trace/events/vmscan.h>
>
> +static unsigned int memcg_v1_min_default_percent;
> +module_param_named(memcg_min, memcg_v1_min_default_percent, uint, 0600);
> +MODULE_PARM_DESC(memcg_min, "memcg v1 min default percent");
> +
> +static unsigned int memcg_v1_low_default_percent;
> +module_param_named(memcg_low, memcg_v1_low_default_percent, uint, 0600);
> +MODULE_PARM_DESC(memcg_low, "memcg v1 low default percent");
> +
> +static unsigned int memcg_v1_high_default_percent;
> +module_param_named(memcg_high, memcg_v1_high_default_percent, uint, 0600);
> +MODULE_PARM_DESC(memcg_high, "memcg v1 high default percent");
This is not the 1990's, why are you using module parameters for this?
And this isn't a module, so why use module options, how are you supposed
to set them?
Ah .. guess I'm a bit out of date.
The can be set either on the kernel command line or through sysfs, nominally
/sys/module/memcontrol/parameters/memcg_high
/sys/module/memcontrol/parameters/memcg_low
/sys/module/memcontrol/parameters/memcg_min
I will look at making these sysctl values instead.
And you didn't document them anywhere?
Next update will include documentation, as appropriate, Thanks!
Also, why is this cc: stable?
Apologies, I understand this is not suitable for stable and will remove the cc.
thanks,
greg k-h
