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Date: Fri, 21 Jun 2024 10:23:31 -0400
From: Kent Overstreet <kent.overstreet@...ux.dev>
To: Yi Sun <yi.sun@...soc.com>
Cc: sunyibuaa@...il.com, tj@...nel.org, jaegeuk@...nel.org,
chao@...nel.org, ebiggers@...gle.com, jiangshanlai@...il.com,
linux-kernel@...r.kernel.org, linux-f2fs-devel@...ts.sourceforge.net, niuzhiguo84@...il.com,
Hao_hao.Wang@...soc.com, yunlongxing23@...il.com
Subject: Re: [PATCH 1/2] workqueue: add io priority to work_struct
On Fri, Jun 21, 2024 at 02:26:16PM +0800, Yi Sun wrote:
> Many works will go to submit_bio(), and in many cases the io priority of
> kworker cannot meet the real-time requirements of this work.
>
> So add the basic attribute ioprio to work_struct, and kworker can adjust
> its io priority according to this attribute.
>
> Add function set_work_ioprio() to set the io priority of this work.
> Add function may_adjust_work_task_ioprio() to adjust kworker's io priority.
> Add function restore_work_task_ioprio() to restore kworker's io priority.
work_struct!?
there's a lot of task_struct properties we would want work_struct to
inherit if we went this route, but it's just not feasible, work_struct
should be small and thin.
You're always embedding work_struct into your own struct, I would
suggest tracking this yourself - or coming up with a new heavier
standard struct that embeds a work_struct and has io path options,
there's more than just priority.
>
> Signed-off-by: Yi Sun <yi.sun@...soc.com>
> ---
> include/linux/workqueue.h | 9 ++++++
> include/linux/workqueue_types.h | 6 ++++
> kernel/workqueue.c | 51 +++++++++++++++++++++++++++++++++
> 3 files changed, 66 insertions(+)
>
> diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
> index fb3993894536..f6191774b730 100644
> --- a/include/linux/workqueue.h
> +++ b/include/linux/workqueue.h
> @@ -286,6 +286,9 @@ static inline unsigned int work_static(struct work_struct *work) { return 0; }
> lockdep_init_map(&(_work)->lockdep_map, "(work_completion)"#_work, (_key), 0); \
> INIT_LIST_HEAD(&(_work)->entry); \
> (_work)->func = (_func); \
> + (_work)->ioprio = 0; \
> + (_work)->ori_ioprio = 0; \
> + (_work)->ioprio_flag = 0; \
> } while (0)
> #else
> #define __INIT_WORK_KEY(_work, _func, _onstack, _key) \
> @@ -294,6 +297,9 @@ static inline unsigned int work_static(struct work_struct *work) { return 0; }
> (_work)->data = (atomic_long_t) WORK_DATA_INIT(); \
> INIT_LIST_HEAD(&(_work)->entry); \
> (_work)->func = (_func); \
> + (_work)->ioprio = 0; \
> + (_work)->ori_ioprio = 0; \
> + (_work)->ioprio_flag = 0; \
> } while (0)
> #endif
>
> @@ -585,6 +591,9 @@ extern struct work_struct *current_work(void);
> extern bool current_is_workqueue_rescuer(void);
> extern bool workqueue_congested(int cpu, struct workqueue_struct *wq);
> extern unsigned int work_busy(struct work_struct *work);
> +extern void set_work_ioprio(struct work_struct *work, unsigned short ioprio);
> +extern void may_adjust_work_task_ioprio(struct work_struct *work);
> +extern void restore_work_task_ioprio(struct work_struct *work);
> extern __printf(1, 2) void set_worker_desc(const char *fmt, ...);
> extern void print_worker_info(const char *log_lvl, struct task_struct *task);
> extern void show_all_workqueues(void);
> diff --git a/include/linux/workqueue_types.h b/include/linux/workqueue_types.h
> index 4c38824f3ab4..d9969596bbc3 100644
> --- a/include/linux/workqueue_types.h
> +++ b/include/linux/workqueue_types.h
> @@ -17,6 +17,12 @@ struct work_struct {
> atomic_long_t data;
> struct list_head entry;
> work_func_t func;
> + /* If the work does submit_bio, io priority may be needed. */
> + unsigned short ioprio;
> + /* Record kworker's original io priority. */
> + unsigned short ori_ioprio;
> + /* Whether the work has set io priority? */
> + long ioprio_flag;
> #ifdef CONFIG_LOCKDEP
> struct lockdep_map lockdep_map;
> #endif
> diff --git a/kernel/workqueue.c b/kernel/workqueue.c
> index 003474c9a77d..a44a8f92eec2 100644
> --- a/kernel/workqueue.c
> +++ b/kernel/workqueue.c
> @@ -55,6 +55,7 @@
> #include <linux/kvm_para.h>
> #include <linux/delay.h>
> #include <linux/irq_work.h>
> +#include <linux/ioprio.h>
>
> #include "workqueue_internal.h"
>
> @@ -6025,6 +6026,56 @@ unsigned int work_busy(struct work_struct *work)
> }
> EXPORT_SYMBOL_GPL(work_busy);
>
> +/**
> + * set_work_ioprio - set io priority for the current work
> + * @work: the work to be set
> + * @ioprio: desired io priority
> + *
> + * This function can be called after INIT_WORK if the io priority
> + * of the work needs to adjust. And it is recommended to use this
> + * function together with may_adjust_work_task_ioprio() and
> + * restore_work_task_ioprio().
> + */
> +void set_work_ioprio(struct work_struct *work, unsigned short ioprio)
> +{
> + work->ioprio = ioprio;
> + work->ioprio_flag = 1;
> +}
> +EXPORT_SYMBOL_GPL(set_work_ioprio);
> +
> +/**
> + * may_adjust_work_task_ioprio - adjust the io priority of kworker
> + * @work: the work that kworker will do
> + *
> + * It is recommended to use this function together with set_work_ioprio()
> + * and restore_work_task_ioprio().
> + */
> +void may_adjust_work_task_ioprio(struct work_struct *work)
> +{
> + if (work->ioprio_flag) {
> + work->ori_ioprio = get_current_ioprio();
> + set_task_ioprio(current, work->ioprio);
> + }
> +}
> +EXPORT_SYMBOL_GPL(may_adjust_work_task_ioprio);
> +
> +/**
> + * restore_work_task_ioprio - restore the io priority of kworker
> + * @work: the work that kworker just did
> + *
> + * When kworker finishes the work, the original io priority of
> + * kworker should be restored. It is recommended to use this function
> + * together with set_work_ioprio() and may_adjust_work_task_ioprio().
> + */
> +void restore_work_task_ioprio(struct work_struct *work)
> +{
> + if (work->ioprio_flag) {
> + set_task_ioprio(current, work->ori_ioprio);
> + work->ioprio_flag = 0;
> + }
> +}
> +EXPORT_SYMBOL_GPL(restore_work_task_ioprio);
> +
> /**
> * set_worker_desc - set description for the current work item
> * @fmt: printf-style format string
> --
> 2.25.1
>
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