From mboxrd@z Thu Jan 1 00:00:00 1970 From: Evgeniy Polyakov Subject: Re: readahead on directories Date: Thu, 22 Apr 2010 00:21:34 +0400 Message-ID: <20100421202134.GB25130@ioremap.net> References: <4BCC7C05.8000803@cfl.rr.com> <20100421004434.GA27420@shareable.org> <4BCF123C.6010400@cfl.rr.com> <20100421161211.GC27575@shareable.org> <20100421183853.GA14897@ioremap.net> <20100421185124.GM27575@shareable.org> <20100421185657.GA21249@ioremap.net> <20100421200243.GU27575@shareable.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Phillip Susi , linux-fsdevel@vger.kernel.org, Linux-kernel To: Jamie Lokier Return-path: Received: from tservice.ru ([195.178.208.66]:40122 "EHLO tservice.net.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756335Ab0DUUVk (ORCPT ); Wed, 21 Apr 2010 16:21:40 -0400 Content-Disposition: inline In-Reply-To: <20100421200243.GU27575@shareable.org> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Wed, Apr 21, 2010 at 09:02:43PM +0100, Jamie Lokier (jamie@shareable.org) wrote: > FIEMAP might not be the answer, but what part of it requires fs > knowledge? It's supposed to be fs-independent. I agree it's not > always appropriate to use, and I don't know if it would be effective > anyway. At least we have to know whether given fs supports such interface. And more complex is to know how underlying fs is organized. What is extent, which types can it have, where exactly information about extent metadata is stored, i.e. where can we find what this object is about? And how to actually populate appropriate blocks into ram to speedup readdir()? FIEMAP (which is file mapper btw :) is useful for information gathering about how fs is organized, but that's all I'm afraid. -- Evgeniy Polyakov