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Open Source and information security mailing list archives
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Date: Wed, 21 Apr 2010 21:39:37 +0100 From: Jamie Lokier <jamie@...reable.org> To: Evgeniy Polyakov <zbr@...emap.net> Cc: Phillip Susi <psusi@....rr.com>, linux-fsdevel@...r.kernel.org, Linux-kernel <linux-kernel@...r.kernel.org> Subject: Re: readahead on directories Evgeniy Polyakov wrote: > On Wed, Apr 21, 2010 at 09:02:43PM +0100, Jamie Lokier (jamie@...reable.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? Ummm... Does any of that matter? > And how to actually populate appropriate blocks into ram to speedup > readdir()? Blockdev readahead() :-) > FIEMAP (which is file mapper btw :) is useful for information gathering > about how fs is organized, but that's all I'm afraid. That's all you need to start fetching from the blockdev. You can't *use* the blockdev data, but that doesn't matter for this readahead operation, only that they are approximately the right data blocks. - Jamie -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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