From e7639bb48d39dd7f544b19c8a09bb62f934b6e32 Mon Sep 17 00:00:00 2001 From: SeongJae Park Date: Sat, 16 Sep 2023 02:09:38 +0000 Subject: mm/damon/sysfs-schemes: use nr_accesses_bp as the source of tried_regions//nr_accesses DAMON sysfs interface exposes access rate of each region via DAMOS tried regions directory. For this, the nr_accesses field of the region is used. DAMOS was actually using nr_accesses in the past, but it uses nr_accesses_bp now. Use the value that it is really using as the source. Note that this doesn't expose nr_accesses_bp as is (in basis point), but after converting it to the natural number by dividing the value by 10,000. Hence there is no behavioral change from users' perspective. Link: https://lkml.kernel.org/r/20230916020945.47296-3-sj@kernel.org Signed-off-by: SeongJae Park Cc: Jonathan Corbet Cc: Shuah Khan Cc: Steven Rostedt (Google) Signed-off-by: Andrew Morton --- mm/damon/sysfs-schemes.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'mm/damon/sysfs-schemes.c') diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c index 527e7d17eb3b..093700f50b18 100644 --- a/mm/damon/sysfs-schemes.c +++ b/mm/damon/sysfs-schemes.c @@ -31,7 +31,7 @@ static struct damon_sysfs_scheme_region *damon_sysfs_scheme_region_alloc( return NULL; sysfs_region->kobj = (struct kobject){}; sysfs_region->ar = region->ar; - sysfs_region->nr_accesses = region->nr_accesses; + sysfs_region->nr_accesses = region->nr_accesses_bp / 10000; sysfs_region->age = region->age; INIT_LIST_HEAD(&sysfs_region->list); return sysfs_region; -- cgit v1.2.3 From 42f994b71404b17abcd6b170de7a6aa95ffe5d4a Mon Sep 17 00:00:00 2001 From: SeongJae Park Date: Sat, 16 Sep 2023 02:09:40 +0000 Subject: mm/damon/core: implement scheme-specific apply interval DAMON-based operation schemes are applied for every aggregation interval. That was mainly because schemes were using nr_accesses, which be complete to be used for every aggregation interval. However, the schemes are now using nr_accesses_bp, which is updated for each sampling interval in a way that reasonable to be used. Therefore, there is no reason to apply schemes for each aggregation interval. The unnecessary alignment with aggregation interval was also making some use cases of DAMOS tricky. Quotas setting under long aggregation interval is one such example. Suppose the aggregation interval is ten seconds, and there is a scheme having CPU quota 100ms per 1s. The scheme will actually uses 100ms per ten seconds, since it cannobe be applied before next aggregation interval. The feature is working as intended, but the results might not that intuitive for some users. This could be fixed by updating the quota to 1s per 10s. But, in the case, the CPU usage of DAMOS could look like spikes, and would actually make a bad effect to other CPU-sensitive workloads. Implement a dedicated timing interval for each DAMON-based operation scheme, namely apply_interval. The interval will be sampling interval aligned, and each scheme will be applied for its apply_interval. The interval is set to 0 by default, and it means the scheme should use the aggregation interval instead. This avoids old users getting any behavioral difference. Link: https://lkml.kernel.org/r/20230916020945.47296-5-sj@kernel.org Signed-off-by: SeongJae Park Cc: Jonathan Corbet Cc: Shuah Khan Cc: Steven Rostedt (Google) Signed-off-by: Andrew Morton --- mm/damon/sysfs-schemes.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'mm/damon/sysfs-schemes.c') diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c index 093700f50b18..3d30e85596b0 100644 --- a/mm/damon/sysfs-schemes.c +++ b/mm/damon/sysfs-schemes.c @@ -1610,7 +1610,7 @@ static struct damos *damon_sysfs_mk_scheme( .low = sysfs_wmarks->low, }; - scheme = damon_new_scheme(&pattern, sysfs_scheme->action, "a, + scheme = damon_new_scheme(&pattern, sysfs_scheme->action, 0, "a, &wmarks); if (!scheme) return NULL; -- cgit v1.2.3 From a2a9f68e358fa9627aa72e7182ad0b82846bda9e Mon Sep 17 00:00:00 2001 From: SeongJae Park Date: Sat, 16 Sep 2023 02:09:42 +0000 Subject: mm/damon/sysfs-schemes: support DAMOS apply interval Update DAMON sysfs interface to support DAMOS apply intervals by adding a new file, 'apply_interval_us' in each scheme directory. Users can set and get the interval for each scheme in microseconds by writing to and reading from the file. Link: https://lkml.kernel.org/r/20230916020945.47296-7-sj@kernel.org Signed-off-by: SeongJae Park Cc: Jonathan Corbet Cc: Shuah Khan Cc: Steven Rostedt (Google) Signed-off-by: Andrew Morton --- mm/damon/sysfs-schemes.c | 38 ++++++++++++++++++++++++++++++++++---- 1 file changed, 34 insertions(+), 4 deletions(-) (limited to 'mm/damon/sysfs-schemes.c') diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c index 3d30e85596b0..a7d70b95c4dd 100644 --- a/mm/damon/sysfs-schemes.c +++ b/mm/damon/sysfs-schemes.c @@ -1121,6 +1121,7 @@ struct damon_sysfs_scheme { struct kobject kobj; enum damos_action action; struct damon_sysfs_access_pattern *access_pattern; + unsigned long apply_interval_us; struct damon_sysfs_quotas *quotas; struct damon_sysfs_watermarks *watermarks; struct damon_sysfs_scheme_filters *filters; @@ -1141,7 +1142,7 @@ static const char * const damon_sysfs_damos_action_strs[] = { }; static struct damon_sysfs_scheme *damon_sysfs_scheme_alloc( - enum damos_action action) + enum damos_action action, unsigned long apply_interval_us) { struct damon_sysfs_scheme *scheme = kmalloc(sizeof(*scheme), GFP_KERNEL); @@ -1150,6 +1151,7 @@ static struct damon_sysfs_scheme *damon_sysfs_scheme_alloc( return NULL; scheme->kobj = (struct kobject){}; scheme->action = action; + scheme->apply_interval_us = apply_interval_us; return scheme; } @@ -1353,6 +1355,25 @@ static ssize_t action_store(struct kobject *kobj, struct kobj_attribute *attr, return -EINVAL; } +static ssize_t apply_interval_us_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + struct damon_sysfs_scheme *scheme = container_of(kobj, + struct damon_sysfs_scheme, kobj); + + return sysfs_emit(buf, "%lu\n", scheme->apply_interval_us); +} + +static ssize_t apply_interval_us_store(struct kobject *kobj, + struct kobj_attribute *attr, const char *buf, size_t count) +{ + struct damon_sysfs_scheme *scheme = container_of(kobj, + struct damon_sysfs_scheme, kobj); + int err = kstrtoul(buf, 0, &scheme->apply_interval_us); + + return err ? err : count; +} + static void damon_sysfs_scheme_release(struct kobject *kobj) { kfree(container_of(kobj, struct damon_sysfs_scheme, kobj)); @@ -1361,8 +1382,12 @@ static void damon_sysfs_scheme_release(struct kobject *kobj) static struct kobj_attribute damon_sysfs_scheme_action_attr = __ATTR_RW_MODE(action, 0600); +static struct kobj_attribute damon_sysfs_scheme_apply_interval_us_attr = + __ATTR_RW_MODE(apply_interval_us, 0600); + static struct attribute *damon_sysfs_scheme_attrs[] = { &damon_sysfs_scheme_action_attr.attr, + &damon_sysfs_scheme_apply_interval_us_attr.attr, NULL, }; ATTRIBUTE_GROUPS(damon_sysfs_scheme); @@ -1413,7 +1438,11 @@ static int damon_sysfs_schemes_add_dirs(struct damon_sysfs_schemes *schemes, schemes->schemes_arr = schemes_arr; for (i = 0; i < nr_schemes; i++) { - scheme = damon_sysfs_scheme_alloc(DAMOS_STAT); + /* + * apply_interval_us as 0 means same to aggregation interval + * (same to before-apply_interval behavior) + */ + scheme = damon_sysfs_scheme_alloc(DAMOS_STAT, 0); if (!scheme) { damon_sysfs_schemes_rm_dirs(schemes); return -ENOMEM; @@ -1610,8 +1639,8 @@ static struct damos *damon_sysfs_mk_scheme( .low = sysfs_wmarks->low, }; - scheme = damon_new_scheme(&pattern, sysfs_scheme->action, 0, "a, - &wmarks); + scheme = damon_new_scheme(&pattern, sysfs_scheme->action, + sysfs_scheme->apply_interval_us, "a, &wmarks); if (!scheme) return NULL; @@ -1641,6 +1670,7 @@ static void damon_sysfs_update_scheme(struct damos *scheme, scheme->pattern.max_age_region = access_pattern->age->max; scheme->action = sysfs_scheme->action; + scheme->apply_interval_us = sysfs_scheme->apply_interval_us; scheme->quota.ms = sysfs_quotas->ms; scheme->quota.sz = sysfs_quotas->sz; -- cgit v1.2.3 From 4d4e41b682990b1dc5bba2bc313800340bf5c2d4 Mon Sep 17 00:00:00 2001 From: SeongJae Park Date: Thu, 12 Oct 2023 19:22:53 +0000 Subject: mm/damon/sysfs-schemes: do not update tried regions more than one DAMON snapshot Patch series "mm/damon/sysfs-schemes: Do DAMOS tried regions update for only one apply interval". DAMOS tried regions update feature of DAMON sysfs interface is doing the update for one aggregation interval after the request is made. Since the per-scheme apply interval is supported, that behavior makes no much sense. That is, the tried regions directory will have regions from multiple DAMON monitoring results snapshots, or no region for apply intervals that much shorter than, or longer than the aggregation interval, respectively. Update the behavior to update the regions for each scheme for only its apply interval, and update the document. Since DAMOS apply interval is the aggregation by default, this change makes no visible behavioral difference to old users who don't explicitly set the apply intervals. Patches Sequence ---------------- The first two patches makes schemes of apply intervals that much shorter or longer than the aggregation interval to keep the maximum and minimum times for continuing the update. After the two patches, the update aligns with the each scheme's apply interval. Finally, the third patch updates the document to reflect the behavior. This patch (of 3): DAMON_SYSFS exposes every DAMON-found region that eligible for applying the scheme action for one aggregation interval. However, each DAMON-based operation scheme has its own apply interval. Hence, for a scheme that having its apply interval much smaller than the aggregation interval, DAMON_SYSFS will expose the scheme regions that applied to more than one DAMON monitoring results snapshots. Since the purpose of DAMON tried regions is exposing single snapshot, this makes no much sense. Track progress of each scheme's tried regions update and avoid the case. Link: https://lkml.kernel.org/r/20231012192256.33556-1-sj@kernel.org Link: https://lkml.kernel.org/r/20231012192256.33556-2-sj@kernel.org Signed-off-by: SeongJae Park Cc: Jonathan Corbet Signed-off-by: Andrew Morton --- mm/damon/sysfs-schemes.c | 77 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 77 insertions(+) (limited to 'mm/damon/sysfs-schemes.c') diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c index a7d70b95c4dd..b07a5c544b34 100644 --- a/mm/damon/sysfs-schemes.c +++ b/mm/damon/sysfs-schemes.c @@ -113,11 +113,47 @@ static const struct kobj_type damon_sysfs_scheme_region_ktype = { * scheme regions directory */ +/* + * enum damos_sysfs_regions_upd_status - Represent DAMOS tried regions update + * status + * @DAMOS_TRIED_REGIONS_UPD_IDLE: Waiting for next request. + * @DAMOS_TRIED_REGIONS_UPD_STARTED: Update started. + * @DAMOS_TRIED_REGIONS_UPD_FINISHED: Update finished. + * + * Each DAMON-based operation scheme (&struct damos) has its own apply + * interval, and we need to expose the scheme tried regions based on only + * single snapshot. For this, we keep the tried regions update status for each + * scheme. The status becomes 'idle' at the beginning. + * + * Once the tried regions update request is received, the request handling + * start function (damon_sysfs_scheme_update_regions_start()) sets the status + * of all schemes as 'idle' again, and register ->before_damos_apply() and + * ->after_sampling() callbacks. + * + * Then, the first followup ->before_damos_apply() callback + * (damon_sysfs_before_damos_apply()) sets the status 'started'. The first + * ->after_sampling() callback (damon_sysfs_after_sampling()) after the call + * is called only after the scheme is completely applied + * to the given snapshot. Hence the callback knows the situation by showing + * 'started' status, and sets the status as 'finished'. Then, + * damon_sysfs_before_damos_apply() understands the situation by showing the + * 'finished' status and do nothing. + * + * Finally, the tried regions request handling finisher function + * (damon_sysfs_schemes_update_regions_stop()) unregisters the callbacks. + */ +enum damos_sysfs_regions_upd_status { + DAMOS_TRIED_REGIONS_UPD_IDLE, + DAMOS_TRIED_REGIONS_UPD_STARTED, + DAMOS_TRIED_REGIONS_UPD_FINISHED, +}; + struct damon_sysfs_scheme_regions { struct kobject kobj; struct list_head regions_list; int nr_regions; unsigned long total_bytes; + enum damos_sysfs_regions_upd_status upd_status; }; static struct damon_sysfs_scheme_regions * @@ -130,6 +166,7 @@ damon_sysfs_scheme_regions_alloc(void) INIT_LIST_HEAD(®ions->regions_list); regions->nr_regions = 0; regions->total_bytes = 0; + regions->upd_status = DAMOS_TRIED_REGIONS_UPD_IDLE; return regions; } @@ -1777,6 +1814,10 @@ static int damon_sysfs_before_damos_apply(struct damon_ctx *ctx, return 0; sysfs_regions = sysfs_schemes->schemes_arr[schemes_idx]->tried_regions; + if (sysfs_regions->upd_status == DAMOS_TRIED_REGIONS_UPD_FINISHED) + return 0; + if (sysfs_regions->upd_status == DAMOS_TRIED_REGIONS_UPD_IDLE) + sysfs_regions->upd_status = DAMOS_TRIED_REGIONS_UPD_STARTED; sysfs_regions->total_bytes += r->ar.end - r->ar.start; if (damos_regions_upd_total_bytes_only) return 0; @@ -1793,6 +1834,29 @@ static int damon_sysfs_before_damos_apply(struct damon_ctx *ctx, return 0; } +/* + * DAMON callback that called after each accesses sampling. While this + * callback is registered, damon_sysfs_lock should be held to ensure the + * regions directories exist. + */ +static int damon_sysfs_after_sampling(struct damon_ctx *ctx) +{ + struct damon_sysfs_schemes *sysfs_schemes = + damon_sysfs_schemes_for_damos_callback; + struct damon_sysfs_scheme_regions *sysfs_regions; + int i; + + for (i = 0; i < sysfs_schemes->nr; i++) { + sysfs_regions = sysfs_schemes->schemes_arr[i]->tried_regions; + if (sysfs_regions->upd_status == + DAMOS_TRIED_REGIONS_UPD_STARTED) + sysfs_regions->upd_status = + DAMOS_TRIED_REGIONS_UPD_FINISHED; + } + + return 0; +} + /* Called from damon_sysfs_cmd_request_callback under damon_sysfs_lock */ int damon_sysfs_schemes_clear_regions( struct damon_sysfs_schemes *sysfs_schemes, @@ -1816,6 +1880,16 @@ int damon_sysfs_schemes_clear_regions( return 0; } +static void damos_tried_regions_init_upd_status( + struct damon_sysfs_schemes *sysfs_schemes) +{ + int i; + + for (i = 0; i < sysfs_schemes->nr; i++) + sysfs_schemes->schemes_arr[i]->tried_regions->upd_status = + DAMOS_TRIED_REGIONS_UPD_IDLE; +} + /* Called from damon_sysfs_cmd_request_callback under damon_sysfs_lock */ int damon_sysfs_schemes_update_regions_start( struct damon_sysfs_schemes *sysfs_schemes, @@ -1823,8 +1897,10 @@ int damon_sysfs_schemes_update_regions_start( { damon_sysfs_schemes_clear_regions(sysfs_schemes, ctx); damon_sysfs_schemes_for_damos_callback = sysfs_schemes; + damos_tried_regions_init_upd_status(sysfs_schemes); damos_regions_upd_total_bytes_only = total_bytes_only; ctx->callback.before_damos_apply = damon_sysfs_before_damos_apply; + ctx->callback.after_sampling = damon_sysfs_after_sampling; return 0; } @@ -1837,6 +1913,7 @@ int damon_sysfs_schemes_update_regions_stop(struct damon_ctx *ctx) { damon_sysfs_schemes_for_damos_callback = NULL; ctx->callback.before_damos_apply = NULL; + ctx->callback.after_sampling = NULL; damon_sysfs_schemes_region_idx = 0; return 0; } -- cgit v1.2.3 From 76126332c7606ba25a4ae5db37145fd526985b45 Mon Sep 17 00:00:00 2001 From: SeongJae Park Date: Thu, 12 Oct 2023 19:22:54 +0000 Subject: mm/damon/sysfs: avoid empty scheme tried regions for large apply interval DAMON_SYSFS assumes all schemes will be applied for at least one DAMON monitoring results snapshot within one aggregation interval, or makes no sense to wait for it while DAMON is deactivated by the watermarks. That for deactivated status still makes sense, but the aggregation interval based assumption is invalid now because each scheme can has its own apply interval. For schemes having larger than the aggregation or watermarks check interval, DAMOS tried regions update request can be finished without the update. Avoid the case by explicitly checking the status of the schemes tried regions update and watermarks based DAMON deactivation. Link: https://lkml.kernel.org/r/20231012192256.33556-3-sj@kernel.org Signed-off-by: SeongJae Park Cc: Jonathan Corbet Signed-off-by: Andrew Morton --- mm/damon/sysfs-schemes.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'mm/damon/sysfs-schemes.c') diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c index b07a5c544b34..45bd0fd4a8b1 100644 --- a/mm/damon/sysfs-schemes.c +++ b/mm/damon/sysfs-schemes.c @@ -1904,6 +1904,22 @@ int damon_sysfs_schemes_update_regions_start( return 0; } +bool damos_sysfs_regions_upd_done(void) +{ + struct damon_sysfs_schemes *sysfs_schemes = + damon_sysfs_schemes_for_damos_callback; + struct damon_sysfs_scheme_regions *sysfs_regions; + int i; + + for (i = 0; i < sysfs_schemes->nr; i++) { + sysfs_regions = sysfs_schemes->schemes_arr[i]->tried_regions; + if (sysfs_regions->upd_status != + DAMOS_TRIED_REGIONS_UPD_FINISHED) + return false; + } + return true; +} + /* * Called from damon_sysfs_cmd_request_callback under damon_sysfs_lock. Caller * should unlock damon_sysfs_lock which held before -- cgit v1.2.3