+/* How urgent is flushing out data? Returns one of several values:
+ * 0 - memory state is fine
+ * 1 - should launch flushd if not already running
+ * 2 - should block writers until memory frees up
+ */
+static int compute_pressure(BlueSkyFS *fs)
+{
+ /* LEVEL 2 */
+ /* Too much dirty data in memory? */
+ if (g_atomic_int_get(&fs->cache_dirty)
+ + g_atomic_int_get(&fs->cache_log_dirty)
+ > bluesky_watermark_high_dirty)
+ {
+ g_print("pressure: too much dirty data (2)\n");
+ return 2;
+ }
+
+ /* Too much uncommitted data in the journal on disk, not yet flushed to the
+ * cloud? */
+ /*printf("Dirty journals: %d to %d\n",
+ fs->log->journal_watermark, fs->log->seq_num);*/
+ int dirty_limit;
+ dirty_limit = bluesky_options.cache_size / (LOG_SEGMENT_SIZE / 1024) / 2;
+ int dirty_journals = fs->log->seq_num - fs->log->journal_watermark + 1;
+ if (dirty_journals > 1 && dirty_journals >= dirty_limit) {
+ printf("pressure: too many dirty journals (%d >= %d) (2)\n",
+ dirty_journals, dirty_limit);
+ return 2;
+ }
+
+ /* LEVEL 1 */
+ if (g_atomic_int_get(&fs->cache_dirty) > bluesky_watermark_medium_dirty) {
+ g_print("pressure: too much dirty data (1)\n");
+ return 1;
+ }
+
+ if (dirty_journals > 1 && dirty_journals > dirty_limit / 2) {
+ printf("pressure: many dirty journals (%d), should start writeback (1)\n",
+ dirty_journals);
+ return 1;
+ }
+
+ return 0;
+}
+