Re: [PATCH 1/1] psi: remove 500ms min window size limitation for triggers

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]


On Wed 01-03-23 11:34:03, Suren Baghdasaryan wrote:
> Current 500ms min window size for psi triggers limits polling interval
> to 50ms to prevent polling threads from using too much cpu bandwidth by
> polling too frequently. However the number of cgroups with triggers is
> unlimited, so this protection can be defeated by creating multiple
> cgroups with psi triggers (triggers in each cgroup are served by a single
> "psimon" kernel thread).
> Instead of limiting min polling period, which also limits the latency of
> psi events, it's better to limit psi trigger creation to authorized users
> only, like we do for system-wide psi triggers (/proc/pressure/* files can
> be written only by processes with CAP_SYS_RESOURCE capability). This also
> makes access rules for cgroup psi files consistent with system-wide ones.
> Add a CAP_SYS_RESOURCE capability check for cgroup psi file writers and
> remove the psi window min size limitation.
> Suggested-by: Sudarshan Rajagopalan <quic_sudaraja@xxxxxxxxxxx>
> Link:
> Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>

Acked-by: Michal Hocko <mhocko@xxxxxxxx>

with this to fix
> @@ -1278,8 +1277,7 @@ struct psi_trigger *psi_trigger_create(struct psi_group *group,
>  	if (state >= PSI_NONIDLE)
>  		return ERR_PTR(-EINVAL);
> -	if (window_us < WINDOW_MIN_US ||
> -		window_us > WINDOW_MAX_US)
> +	if (window_us <= 0 || window_us > WINDOW_MAX_US)
>  		return ERR_PTR(-EINVAL);

window_us is u32 sp the check for <= 0 doesn't make any sense.

>  	/* Check threshold */
> -- 
> 2.40.0.rc0.216.gc4246ad0f0-goog

Michal Hocko

[Index of Archives]     [Linux ARM Kernel]     [Linux ARM]     [Linux Omap]     [Fedora ARM]     [IETF Annouce]     [Security]     [Bugtraq]     [Linux OMAP]     [Linux MIPS]     [eCos]     [Asterisk Internet PBX]     [Linux API]     [Monitors]

  Powered by Linux