diff --git a/include/linux/damon.h b/include/linux/damon.h index ac2d42a50751..2889de3526c3 100644 --- a/include/linux/damon.h +++ b/include/linux/damon.h @@ -352,6 +352,31 @@ struct damos_filter { struct list_head list; }; +struct damon_ctx; +struct damos; + +/** + * struct damos_walk_control - Control damos_walk(). + * + * @walk_fn: Function to be called back for each region. + * @data: Data that will be passed to walk functions. + * + * Control damos_walk(), which requests specific kdamond to invoke the given + * function to each region that eligible to apply actions of the kdamond's + * schemes. Refer to damos_walk() for more details. + */ +struct damos_walk_control { + void (*walk_fn)(void *data, struct damon_ctx *ctx, + struct damon_target *t, struct damon_region *r, + struct damos *s); + void *data; +/* private: internal use only */ + /* informs if the kdamond finished handling of the walk request */ + struct completion completion; + /* informs if the walk is canceled. */ + bool canceled; +}; + /** * struct damos_access_pattern - Target access pattern of the given scheme. * @min_sz_region: Minimum size of target regions. @@ -415,6 +440,8 @@ struct damos { * @action */ unsigned long next_apply_sis; + /* informs if ongoing DAMOS walk for this scheme is finished */ + bool walk_completed; /* public: */ struct damos_quota quota; struct damos_watermarks wmarks; @@ -442,8 +469,6 @@ enum damon_ops_id { NR_DAMON_OPS, }; -struct damon_ctx; - /** * struct damon_operations - Monitoring operations for given use cases. * @@ -656,6 +681,9 @@ struct damon_ctx { struct damon_call_control *call_control; struct mutex call_control_lock; + struct damos_walk_control *walk_control; + struct mutex walk_control_lock; + /* public: */ struct task_struct *kdamond; struct mutex kdamond_lock; @@ -804,6 +832,7 @@ int damon_start(struct damon_ctx **ctxs, int nr_ctxs, bool exclusive); int damon_stop(struct damon_ctx **ctxs, int nr_ctxs); int damon_call(struct damon_ctx *ctx, struct damon_call_control *control); +int damos_walk(struct damon_ctx *ctx, struct damos_walk_control *control); int damon_set_region_biggest_system_ram_default(struct damon_target *t, unsigned long *start, unsigned long *end); diff --git a/mm/damon/core.c b/mm/damon/core.c index 97f19ec4179c..d02a7d6da855 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -505,6 +505,7 @@ struct damon_ctx *damon_new_ctx(void) mutex_init(&ctx->kdamond_lock); mutex_init(&ctx->call_control_lock); + mutex_init(&ctx->walk_control_lock); ctx->attrs.min_nr_regions = 10; ctx->attrs.max_nr_regions = 1000; @@ -1211,6 +1212,46 @@ int damon_call(struct damon_ctx *ctx, struct damon_call_control *control) return 0; } +/** + * damos_walk() - Invoke a given functions while DAMOS walk regions. + * @ctx: DAMON context to call the functions for. + * @control: Control variable of the walk request. + * + * Ask DAMON worker thread (kdamond) of @ctx to call a function for each region + * that the kdamond will apply DAMOS action to, and wait until the kdamond + * finishes handling of the request. + * + * The kdamond executes the given function in the main loop, for each region + * just after it applied any DAMOS actions of @ctx to it. The invocation is + * made only within one &damos->apply_interval_us since damos_walk() + * invocation, for each scheme. The given callback function can hence safely + * access the internal data of &struct damon_ctx and &struct damon_region that + * each of the scheme will apply the action for next interval, without + * additional synchronizations against the kdamond. If every scheme of @ctx + * passed at least one &damos->apply_interval_us, kdamond marks the request as + * completed so that damos_walk() can wakeup and return. + * + * Return: 0 on success, negative error code otherwise. + */ +int damos_walk(struct damon_ctx *ctx, struct damos_walk_control *control) +{ + init_completion(&control->completion); + control->canceled = false; + mutex_lock(&ctx->walk_control_lock); + if (ctx->walk_control) { + mutex_unlock(&ctx->walk_control_lock); + return -EBUSY; + } + ctx->walk_control = control; + mutex_unlock(&ctx->walk_control_lock); + if (!damon_is_running(ctx)) + return -EINVAL; + wait_for_completion(&control->completion); + if (control->canceled) + return -ECANCELED; + return 0; +} + /* * Reset the aggregated monitoring results ('nr_accesses' of each region). */ @@ -1390,6 +1431,91 @@ static bool damos_filter_out(struct damon_ctx *ctx, struct damon_target *t, return false; } +/* + * damos_walk_call_walk() - Call &damos_walk_control->walk_fn. + * @ctx: The context of &damon_ctx->walk_control. + * @t: The monitoring target of @r that @s will be applied. + * @r: The region of @t that @s will be applied. + * @s: The scheme of @ctx that will be applied to @r. + * + * This function is called from kdamond whenever it asked the operation set to + * apply a DAMOS scheme action to a region. If a DAMOS walk request is + * installed by damos_walk() and not yet uninstalled, invoke it. + */ +static void damos_walk_call_walk(struct damon_ctx *ctx, struct damon_target *t, + struct damon_region *r, struct damos *s) +{ + struct damos_walk_control *control; + + mutex_lock(&ctx->walk_control_lock); + control = ctx->walk_control; + mutex_unlock(&ctx->walk_control_lock); + if (!control) + return; + control->walk_fn(control->data, ctx, t, r, s); +} + +/* + * damos_walk_complete() - Complete DAMOS walk request if all walks are done. + * @ctx: The context of &damon_ctx->walk_control. + * @s: A scheme of @ctx that all walks are now done. + * + * This function is called when kdamond finished applying the action of a DAMOS + * scheme to all regions that eligible for the given &damos->apply_interval_us. + * If every scheme of @ctx including @s now finished walking for at least one + * &damos->apply_interval_us, this function makrs the handling of the given + * DAMOS walk request is done, so that damos_walk() can wake up and return. + */ +static void damos_walk_complete(struct damon_ctx *ctx, struct damos *s) +{ + struct damos *siter; + struct damos_walk_control *control; + + mutex_lock(&ctx->walk_control_lock); + control = ctx->walk_control; + mutex_unlock(&ctx->walk_control_lock); + if (!control) + return; + + s->walk_completed = true; + /* if all schemes completed, signal completion to walker */ + damon_for_each_scheme(siter, ctx) { + if (!siter->walk_completed) + return; + } + complete(&control->completion); + mutex_lock(&ctx->walk_control_lock); + ctx->walk_control = NULL; + mutex_unlock(&ctx->walk_control_lock); +} + +/* + * damos_walk_cancel() - Cancel the current DAMOS walk request. + * @ctx: The context of &damon_ctx->walk_control. + * + * This function is called when @ctx is deactivated by DAMOS watermarks, DAMOS + * walk is requested but there is no DAMOS scheme to walk for, or the kdamond + * is already out of the main loop and therefore gonna be terminated, and hence + * cannot continue the walks. This function therefore marks the walk request + * as canceled, so that damos_walk() can wake up and return. + */ +static void damos_walk_cancel(struct damon_ctx *ctx) +{ + struct damos_walk_control *control; + + mutex_lock(&ctx->walk_control_lock); + control = ctx->walk_control; + mutex_unlock(&ctx->walk_control_lock); + + if (!control) + return; + control->canceled = true; + complete(&control->completion); + mutex_lock(&ctx->walk_control_lock); + ctx->walk_control = NULL; + mutex_unlock(&ctx->walk_control_lock); +} + static void damos_apply_scheme(struct damon_ctx *c, struct damon_target *t, struct damon_region *r, struct damos *s) { @@ -1444,6 +1570,7 @@ static void damos_apply_scheme(struct damon_ctx *c, struct damon_target *t, damon_nr_regions(t), do_trace); sz_applied = c->ops.apply_scheme(c, t, r, s); } + damos_walk_call_walk(c, t, r, s); ktime_get_coarse_ts64(&end); quota->total_charged_ns += timespec64_to_ns(&end) - timespec64_to_ns(&begin); @@ -1712,6 +1839,7 @@ static void kdamond_apply_schemes(struct damon_ctx *c) damon_for_each_scheme(s, c) { if (c->passed_sample_intervals < s->next_apply_sis) continue; + damos_walk_complete(c, s); s->next_apply_sis = c->passed_sample_intervals + (s->apply_interval_us ? s->apply_interval_us : c->attrs.aggr_interval) / sample_interval; @@ -2024,6 +2152,7 @@ static int kdamond_wait_activation(struct damon_ctx *ctx) ctx->callback.after_wmarks_check(ctx)) break; kdamond_call(ctx, true); + damos_walk_cancel(ctx); } return -EBUSY; } @@ -2117,6 +2246,8 @@ static int kdamond_fn(void *data) */ if (!list_empty(&ctx->schemes)) kdamond_apply_schemes(ctx); + else + damos_walk_cancel(ctx); sample_interval = ctx->attrs.sample_interval ? ctx->attrs.sample_interval : 1; @@ -2157,6 +2288,7 @@ static int kdamond_fn(void *data) mutex_unlock(&ctx->kdamond_lock); kdamond_call(ctx, true); + damos_walk_cancel(ctx); mutex_lock(&damon_lock); nr_running_ctxs--;