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| author | Vladimír Čunát <vladimir.cunat@nic.cz> | 2020-06-09 08:09:32 +0200 |
|---|---|---|
| committer | Tomas Krizek <tomas.krizek@nic.cz> | 2020-06-29 14:25:32 +0200 |
| commit | 26cf29390b2acfe8c6b0547532474ae53763cf42 (patch) | |
| tree | 58617ebbeae3fad8139294414555fcafd9495edc /utils/cache_gc | |
| parent | gc: fix flushing of messages to logs (diff) | |
| download | knot-resolver-26cf29390b2acfe8c6b0547532474ae53763cf42.tar.xz knot-resolver-26cf29390b2acfe8c6b0547532474ae53763cf42.zip | |
gc: fix integer overflow when computing how much to GC
On 32-bit systems the insufficient GC could commonly happen:
https://lists.nic.cz/pipermail/knot-resolver-users/2020/000265.html
The meaning of -f parameter got slightly changed, so that the buggy
computation could be greatly simplified. GC seems to make sense when
most of cache space is used, in which case the difference is small.
Diffstat (limited to 'utils/cache_gc')
| -rw-r--r-- | utils/cache_gc/kr_cache_gc.c | 4 | ||||
| -rw-r--r-- | utils/cache_gc/kr_cache_gc.h | 2 | ||||
| -rw-r--r-- | utils/cache_gc/main.c | 2 |
3 files changed, 4 insertions, 4 deletions
diff --git a/utils/cache_gc/kr_cache_gc.c b/utils/cache_gc/kr_cache_gc.c index 6ba8aad6..a4c04959 100644 --- a/utils/cache_gc/kr_cache_gc.c +++ b/utils/cache_gc/kr_cache_gc.c @@ -217,8 +217,8 @@ int kr_cache_gc(kr_cache_gc_cfg_t *cfg, kr_cache_gc_state_t **state) for (int i = 0; i < CATEGORIES; ++i) { cats_sumsize += cats.categories_sizes[i]; } - ssize_t amount_tofree = knot_db_lmdb_get_mapsize(db) * cfg->cache_to_be_freed - * cats_sumsize / (100 * knot_db_lmdb_get_usage(db)); + /* use less precise variant to avoid 32-bit overflow */ + ssize_t amount_tofree = cats_sumsize / 100 * cfg->cache_to_be_freed; #ifdef DEBUG printf("tofree: %zd\n", amount_tofree); diff --git a/utils/cache_gc/kr_cache_gc.h b/utils/cache_gc/kr_cache_gc.h index 261115d0..839e553d 100644 --- a/utils/cache_gc/kr_cache_gc.h +++ b/utils/cache_gc/kr_cache_gc.h @@ -25,7 +25,7 @@ typedef struct { unsigned long rw_txn_delay; // waiting time between two RW transactions in usecs uint8_t cache_max_usage; // maximum cache usage before triggering GC (percent) - uint8_t cache_to_be_freed; // percent of cache to be freed during GC + uint8_t cache_to_be_freed; // percent of current cache usage to be freed during GC bool dry_run; } kr_cache_gc_cfg_t; diff --git a/utils/cache_gc/main.c b/utils/cache_gc/main.c index cd868553..41654c84 100644 --- a/utils/cache_gc/main.c +++ b/utils/cache_gc/main.c @@ -36,7 +36,7 @@ static void print_help() printf(" -l <deletes_per_txn>\n"); printf(" -m <rw_txn_duration(usecs)>\n"); printf(" -u <cache_max_usage(percent)>\n"); - printf(" -f <cache_to_be_freed(percent)>\n"); + printf(" -f <cache_to_be_freed(percent-of-current-usage)>\n"); printf(" -w <wait_next_rw_txn(usecs)>\n"); printf(" -t <temporary_memory(MBytes)>\n"); printf(" -n (= dry run)\n"); |