From 11ab43084b10cf53b530cdc3a6036c898b79ca38 Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Sat, 14 Aug 2010 02:13:26 +0930 Subject: tdb: workaround starvation problem in locking entire database. We saw tdb_lockall() take 71 seconds under heavy load; this is because Linux (at least) doesn't prevent new small locks being obtained while we're waiting for a big log. The workaround is to do divide and conquer using non-blocking chainlocks: if we get down to a single chain we block. Using a simple test program where children did "hold lock for 100ms, sleep for 1 second" the time to do tdb_lockall() dropped signifiantly. There are ln(hashsize) locks taken in the contended case, but that's slow anyway. More analysis is given in my blog at http://rusty.ozlabs.org/?p=120 This may also help transactions, though in that case it's the initial read lock which uses this gradual locking routine; the update-to-write-lock code is separate and still tries to update in one go. Even though ABI doesn't change, minor version bumped so behavior change can be easily detected. Signed-off-by: Rusty Russell --- lib/tdb/ABI/tdb-1.2.3.sigs | 60 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 60 insertions(+) create mode 100644 lib/tdb/ABI/tdb-1.2.3.sigs (limited to 'lib/tdb/ABI') diff --git a/lib/tdb/ABI/tdb-1.2.3.sigs b/lib/tdb/ABI/tdb-1.2.3.sigs new file mode 100644 index 0000000000..043790d27e --- /dev/null +++ b/lib/tdb/ABI/tdb-1.2.3.sigs @@ -0,0 +1,60 @@ +tdb_add_flags: void (struct tdb_context *, unsigned int) +tdb_append: int (struct tdb_context *, TDB_DATA, TDB_DATA) +tdb_chainlock: int (struct tdb_context *, TDB_DATA) +tdb_chainlock_mark: int (struct tdb_context *, TDB_DATA) +tdb_chainlock_nonblock: int (struct tdb_context *, TDB_DATA) +tdb_chainlock_read: int (struct tdb_context *, TDB_DATA) +tdb_chainlock_unmark: int (struct tdb_context *, TDB_DATA) +tdb_chainunlock: int (struct tdb_context *, TDB_DATA) +tdb_chainunlock_read: int (struct tdb_context *, TDB_DATA) +tdb_check: int (struct tdb_context *, int (*)(TDB_DATA, TDB_DATA, void *), void *) +tdb_close: int (struct tdb_context *) +tdb_delete: int (struct tdb_context *, TDB_DATA) +tdb_dump_all: void (struct tdb_context *) +tdb_enable_seqnum: void (struct tdb_context *) +tdb_error: enum TDB_ERROR (struct tdb_context *) +tdb_errorstr: const char *(struct tdb_context *) +tdb_exists: int (struct tdb_context *, TDB_DATA) +tdb_fd: int (struct tdb_context *) +tdb_fetch: TDB_DATA (struct tdb_context *, TDB_DATA) +tdb_firstkey: TDB_DATA (struct tdb_context *) +tdb_freelist_size: int (struct tdb_context *) +tdb_get_flags: int (struct tdb_context *) +tdb_get_logging_private: void *(struct tdb_context *) +tdb_get_seqnum: int (struct tdb_context *) +tdb_hash_size: int (struct tdb_context *) +tdb_increment_seqnum_nonblock: void (struct tdb_context *) +tdb_lockall: int (struct tdb_context *) +tdb_lockall_mark: int (struct tdb_context *) +tdb_lockall_nonblock: int (struct tdb_context *) +tdb_lockall_read: int (struct tdb_context *) +tdb_lockall_read_nonblock: int (struct tdb_context *) +tdb_lockall_unmark: int (struct tdb_context *) +tdb_log_fn: tdb_log_func (struct tdb_context *) +tdb_map_size: size_t (struct tdb_context *) +tdb_name: const char *(struct tdb_context *) +tdb_nextkey: TDB_DATA (struct tdb_context *, TDB_DATA) +tdb_null: dptr = 0xXXXX, dsize = 0 +tdb_open: struct tdb_context *(const char *, int, int, int, mode_t) +tdb_open_ex: struct tdb_context *(const char *, int, int, int, mode_t, const struct tdb_logging_context *, tdb_hash_func) +tdb_parse_record: int (struct tdb_context *, TDB_DATA, int (*)(TDB_DATA, TDB_DATA, void *), void *) +tdb_printfreelist: int (struct tdb_context *) +tdb_remove_flags: void (struct tdb_context *, unsigned int) +tdb_reopen: int (struct tdb_context *) +tdb_reopen_all: int (int) +tdb_repack: int (struct tdb_context *) +tdb_set_logging_function: void (struct tdb_context *, const struct tdb_logging_context *) +tdb_set_max_dead: void (struct tdb_context *, int) +tdb_setalarm_sigptr: void (struct tdb_context *, volatile sig_atomic_t *) +tdb_store: int (struct tdb_context *, TDB_DATA, TDB_DATA, int) +tdb_transaction_cancel: int (struct tdb_context *) +tdb_transaction_commit: int (struct tdb_context *) +tdb_transaction_prepare_commit: int (struct tdb_context *) +tdb_transaction_start: int (struct tdb_context *) +tdb_transaction_start_nonblock: int (struct tdb_context *) +tdb_traverse: int (struct tdb_context *, tdb_traverse_func, void *) +tdb_traverse_read: int (struct tdb_context *, tdb_traverse_func, void *) +tdb_unlockall: int (struct tdb_context *) +tdb_unlockall_read: int (struct tdb_context *) +tdb_validate_freelist: int (struct tdb_context *, int *) +tdb_wipe_all: int (struct tdb_context *) -- cgit