diff --git a/include/linux/damon.h b/include/linux/damon.h index a67f2c4940e9..ac2d42a50751 100644 --- a/include/linux/damon.h +++ b/include/linux/damon.h @@ -552,6 +552,27 @@ struct damon_callback { void (*before_terminate)(struct damon_ctx *context); }; +/* + * struct damon_call_control - Control damon_call(). + * + * @fn: Function to be called back. + * @data: Data that will be passed to @fn. + * @return_code: Return code from @fn invocation. + * + * Control damon_call(), which requests specific kdamond to invoke a given + * function. Refer to damon_call() for more details. + */ +struct damon_call_control { + int (*fn)(void *data); + void *data; + int return_code; +/* private: internal use only */ + /* informs if the kdamond finished handling of the request */ + struct completion completion; + /* informs if the kdamond canceled @fn infocation */ + bool canceled; +}; + /** * struct damon_attrs - Monitoring attributes for accuracy/overhead control. * @@ -632,6 +653,9 @@ struct damon_ctx { /* for scheme quotas prioritization */ unsigned long *regions_score_histogram; + struct damon_call_control *call_control; + struct mutex call_control_lock; + /* public: */ struct task_struct *kdamond; struct mutex kdamond_lock; @@ -779,6 +803,8 @@ static inline unsigned int damon_max_nr_accesses(const struct damon_attrs *attrs 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 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 5192ee29f6cf..97f19ec4179c 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -504,6 +504,7 @@ struct damon_ctx *damon_new_ctx(void) ctx->next_ops_update_sis = 0; mutex_init(&ctx->kdamond_lock); + mutex_init(&ctx->call_control_lock); ctx->attrs.min_nr_regions = 10; ctx->attrs.max_nr_regions = 1000; @@ -1162,6 +1163,54 @@ int damon_stop(struct damon_ctx **ctxs, int nr_ctxs) return err; } +static bool damon_is_running(struct damon_ctx *ctx) +{ + bool running; + + mutex_lock(&ctx->kdamond_lock); + running = ctx->kdamond != NULL; + mutex_unlock(&ctx->kdamond_lock); + return running; +} + +/** + * damon_call() - Invoke a given function on DAMON worker thread (kdamond). + * @ctx: DAMON context to call the function for. + * @control: Control variable of the call request. + * + * Ask DAMON worker thread (kdamond) of @ctx to call a function with an + * argument data that respectively passed via &damon_call_control->fn and + * &damon_call_control->data of @control, and wait until the kdamond finishes + * handling of the request. + * + * The kdamond executes the function with the argument in the main loop, just + * after a sampling of the iteration is finished. The function can hence + * safely access the internal data of the &struct damon_ctx without additional + * synchronization. The return value of the function will be saved in + * &damon_call_control->return_code. + * + * Return: 0 on success, negative error code otherwise. + */ +int damon_call(struct damon_ctx *ctx, struct damon_call_control *control) +{ + init_completion(&control->completion); + control->canceled = false; + + mutex_lock(&ctx->call_control_lock); + if (ctx->call_control) { + mutex_unlock(&ctx->call_control_lock); + return -EBUSY; + } + ctx->call_control = control; + mutex_unlock(&ctx->call_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). */ @@ -1917,6 +1966,39 @@ static void kdamond_usleep(unsigned long usecs) usleep_range_idle(usecs, usecs + 1); } +/* + * kdamond_call() - handle damon_call_control. + * @ctx: The &struct damon_ctx of the kdamond. + * @cancel: Whether to cancel the invocation of the function. + * + * If there is a &struct damon_call_control request that registered via + * &damon_call() on @ctx, do or cancel the invocation of the function depending + * on @cancel. @cancel is set when the kdamond is deactivated by DAMOS + * watermarks, or the kdamond is already out of the main loop and therefore + * will be terminated. + */ +static void kdamond_call(struct damon_ctx *ctx, bool cancel) +{ + struct damon_call_control *control; + int ret = 0; + + mutex_lock(&ctx->call_control_lock); + control = ctx->call_control; + mutex_unlock(&ctx->call_control_lock); + if (!control) + return; + if (cancel) { + control->canceled = true; + } else { + ret = control->fn(control->data); + control->return_code = ret; + } + complete(&control->completion); + mutex_lock(&ctx->call_control_lock); + ctx->call_control = NULL; + mutex_unlock(&ctx->call_control_lock); +} + /* Returns negative error code if it's not activated but should return */ static int kdamond_wait_activation(struct damon_ctx *ctx) { @@ -1941,6 +2023,7 @@ static int kdamond_wait_activation(struct damon_ctx *ctx) if (ctx->callback.after_wmarks_check && ctx->callback.after_wmarks_check(ctx)) break; + kdamond_call(ctx, true); } return -EBUSY; } @@ -2011,6 +2094,7 @@ static int kdamond_fn(void *data) if (ctx->callback.after_sampling && ctx->callback.after_sampling(ctx)) break; + kdamond_call(ctx, false); kdamond_usleep(sample_interval); ctx->passed_sample_intervals++; @@ -2072,6 +2156,8 @@ done: ctx->kdamond = NULL; mutex_unlock(&ctx->kdamond_lock); + kdamond_call(ctx, true); + mutex_lock(&damon_lock); nr_running_ctxs--; if (!nr_running_ctxs && running_exclusive_ctxs)