Date: Tue, 05 Feb 2008 13:43:47 -0700 From: Scott Long <scottl@samsco.org> To: Andriy Gapon <avg@icyb.net.ua> Cc: Bruce Evans <bde@zeta.org.au>, freebsd-hackers@FreeBSD.org, scottl@FreeBSD.org, freebsd-fs@FreeBSD.org, pav@FreeBSD.org, Julian Elischer <julian@elischer.org>, Remko Lodder <remko@FreeBSD.org> Subject: Re: fs/udf: vm pages "overlap" while reading large dir [patch] Message-ID: <47A8CA83.1000405@samsco.org> In-Reply-To: <47A8754C.5010607@icyb.net.ua> References: <200612221824.kBMIOhfM049471@freefall.freebsd.org> <47A2EDB0.8000801@icyb.net.ua> <47A2F404.7010208@icyb.net.ua> <47A735A4.3060506@icyb.net.ua> <47A75B47.2040604@elischer.org> <1202155663.62432.0.camel@ikaros.oook.cz> <47A8754C.5010607@icyb.net.ua>
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Andriy Gapon wrote: > on 04/02/2008 22:07 Pav Lucistnik said the following: >> Julian Elischer píše v po 04. 02. 2008 v 10:36 -0800: >>> Andriy Gapon wrote: >>>> More on the problem with reading big directories on UDF. >>> You do realise that you have now made yourself the official >>> maintainer of the UDF file system by submitting a competent >>> and insightful analysis of the problem? >> Yay, and can you fix the sequential read performance while you're at it? >> Kthx! >> > > Pav, > > this was almost trivial :-) > See the attached patch, first hunk is just for consistency. > The code was borrowed from cd9660, only field/variable names are adjusted. > Your patch looks reasonable. Btw, for the same reason that read-ahead makes file reading much faster, I would not change directory reading to be 1 sector at a time (unless you also do read-ahead for it). > But there is another issue that I also mentioned in the email about > directory reading. It is UDF_INVALID_BMAP case of udf_bmap_internal, > i.e. the case when file data is embedded into a file entry. > This is a special case that needs to be handled differently. > udf_readatoffset() handles it, but the latest udf_read code doesn't. > I have a real UDF filesystem where this type of allocation is used for > small files and those files can not be read. Oh, so directory data can also follow this convention? Blah. Feel free to fix that too if you want =-) Scott
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