diff options
Diffstat (limited to 'database/engine/pagecache.c')
| -rw-r--r-- | database/engine/pagecache.c | 36 |
1 files changed, 29 insertions, 7 deletions
diff --git a/database/engine/pagecache.c b/database/engine/pagecache.c index 457bcb21..a419ba98 100644 --- a/database/engine/pagecache.c +++ b/database/engine/pagecache.c @@ -209,9 +209,31 @@ static void pg_cache_release_pages(struct rrdengine_instance *ctx, unsigned numb pg_cache_release_pages_unsafe(ctx, number); uv_rwlock_wrunlock(&pg_cache->pg_cache_rwlock); } + +/* + * This function returns the maximum number of pages allowed in the page cache. + * The caller must hold the page cache lock. + */ +static inline unsigned long pg_cache_hard_limit(struct rrdengine_instance *ctx) +{ + /* it's twice the number of producers since we pin 2 pages per producer */ + return ctx->max_cache_pages + 2 * (unsigned long)ctx->stats.metric_API_producers; +} + +/* + * This function returns the low watermark number of pages in the page cache. The page cache should strive to keep the + * number of pages below that number. + * The caller must hold the page cache lock. + */ +static inline unsigned long pg_cache_soft_limit(struct rrdengine_instance *ctx) +{ + /* it's twice the number of producers since we pin 2 pages per producer */ + return ctx->cache_pages_low_watermark + 2 * (unsigned long)ctx->stats.metric_API_producers; +} + /* * This function will block until it reserves #number populated pages. - * It will trigger evictions or dirty page flushing if the ctx->max_cache_pages limit is hit. + * It will trigger evictions or dirty page flushing if the pg_cache_hard_limit() limit is hit. */ static void pg_cache_reserve_pages(struct rrdengine_instance *ctx, unsigned number) { @@ -223,10 +245,10 @@ static void pg_cache_reserve_pages(struct rrdengine_instance *ctx, unsigned numb assert(number < ctx->max_cache_pages); uv_rwlock_wrlock(&pg_cache->pg_cache_rwlock); - if (pg_cache->populated_pages + number >= ctx->max_cache_pages + 1) + if (pg_cache->populated_pages + number >= pg_cache_hard_limit(ctx) + 1) debug(D_RRDENGINE, "==Page cache full. Reserving %u pages.==", number); - while (pg_cache->populated_pages + number >= ctx->max_cache_pages + 1) { + while (pg_cache->populated_pages + number >= pg_cache_hard_limit(ctx) + 1) { if (!pg_cache_try_evict_one_page_unsafe(ctx)) { /* failed to evict */ @@ -260,7 +282,7 @@ static void pg_cache_reserve_pages(struct rrdengine_instance *ctx, unsigned numb /* * This function will attempt to reserve #number populated pages. - * It may trigger evictions if the ctx->cache_pages_low_watermark limit is hit. + * It may trigger evictions if the pg_cache_soft_limit() limit is hit. * Returns 0 on failure and 1 on success. */ static int pg_cache_try_reserve_pages(struct rrdengine_instance *ctx, unsigned number) @@ -272,7 +294,7 @@ static int pg_cache_try_reserve_pages(struct rrdengine_instance *ctx, unsigned n assert(number < ctx->max_cache_pages); uv_rwlock_wrlock(&pg_cache->pg_cache_rwlock); - if (pg_cache->populated_pages + number >= ctx->cache_pages_low_watermark + 1) { + if (pg_cache->populated_pages + number >= pg_cache_soft_limit(ctx) + 1) { debug(D_RRDENGINE, "==Page cache full. Trying to reserve %u pages.==", number); @@ -280,11 +302,11 @@ static int pg_cache_try_reserve_pages(struct rrdengine_instance *ctx, unsigned n if (!pg_cache_try_evict_one_page_unsafe(ctx)) break; ++count; - } while (pg_cache->populated_pages + number >= ctx->cache_pages_low_watermark + 1); + } while (pg_cache->populated_pages + number >= pg_cache_soft_limit(ctx) + 1); debug(D_RRDENGINE, "Evicted %u pages.", count); } - if (pg_cache->populated_pages + number < ctx->max_cache_pages + 1) { + if (pg_cache->populated_pages + number < pg_cache_hard_limit(ctx) + 1) { pg_cache->populated_pages += number; ret = 1; /* success */ } |