On 4/21/2010 4:01 PM, Jamie Lokier wrote: > Ok, this discussion has got a bit confused. Text above refers to > needing to asynchronously read next block in a directory, but if they > are small then that's not important. It is very much important since if you ready each small directory one block at a time, it is very slow. You want to queue up reads to all of them at once so they can be batched. > FIEMAP suggestion is only if you think you need to issue reads for > multiple blocks in the _same_ directory in parallel. From what you say, > I doubt that's important. That may be why you suggested it, but it is also exactly what readahead() does. It also queues the read asynchronously which is what I really want so that I can queue more reads on other directories in one big batch. > That was my first suggestion: threads with readdir(); I thought it had > been rejected hence the further discussion. Yes, it was sort of rejected, which is why I said it's just a workaround for now until readahead() works on directories. It will produce the desired IO pattern but at the expense of ram and cpu cycles creating a bunch of short lived threads that go to sleep almost immediately after being created, and exit when they wake up. readahead() would be much more efficient. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
