+ # default value of file_cache is 0, this tells KeepBlockCache to
+ # choose a default based on whether disk_cache is enabled or not.
+
+ block_cache = arvados.keep.KeepBlockCache(cache_max=self.args.file_cache,
+ disk_cache=self.args.disk_cache,
+ disk_cache_dir=self.args.disk_cache_dir)
+
+ # If there's too many prefetch threads and you
+ # max out the CPU, delivering data to the FUSE
+ # layer actually ends up being slower.
+ # Experimentally, capping 7 threads seems to
+ # be a sweet spot.
+ prefetch_threads = min(max((block_cache.cache_max // (64 * 1024 * 1024)) - 1, 1), 7)
+