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[Bacula-bugs] [bacula 0001704]: FIOBMAP suboptimal for sparse files - FIOEMAP better.
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From: Mantis B. T. <no...@bu...> - 2011-12-31 09:15:32
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The following issue has been CLOSED ====================================================================== http://bugs.bacula.org/view.php?id=1704 ====================================================================== Reported By: stoatwblr Assigned To: ebollengier ====================================================================== Project: bacula Issue ID: 1704 Category: File Daemon Reproducibility: always Severity: minor Priority: normal Status: closed Resolution: no change required Fixed in Version: ====================================================================== Date Submitted: 2011-03-08 17:36 UTC Last Modified: 2011-12-31 09:15 UTC ====================================================================== Summary: FIOBMAP suboptimal for sparse files - FIOEMAP better. Description: Recommended LWN article: SEEK_HOLE or FIEMAP? http://lwn.net/Articles/260795/ "When an application wants to know how a file is store in the disk (for example, a backup application that wants to know if a file is a sparse file and wants to avoid backing up the hole) it uses the fibmap ioctl. But this ioctl is suboptimal - the ioctl can only be asked for a block at a time, which is too expensive for big files. The FIEMAP ioctl, in the other hand, returns a list of extents." Many other OSes have the same (or equivalent) ioctl. Using FIEMAP would allow automatic handling of sparse files without incurring the speed penalties associated with FIOBMAP Steps to Reproduce: Create sparse files, access using FIOBMAP and FIOMAP, time the difference. ====================================================================== ---------------------------------------------------------------------- (0005800) ebollengier (administrator) - 2011-03-17 10:19 http://bugs.bacula.org/view.php?id=1704#c5800 ---------------------------------------------------------------------- Thanks for your proposal, unfortunately, we deal only with Bugs in this tool. For new features, see www.bacula.org -> New Features. For your information, Bacula already supports Sparse file with a very simple and portable scheme. Unless you show us (with real data) that your idea improve the throughput or the cpu usage by a reasonable factor, we won't change the current code. ---------------------------------------------------------------------- (0005804) stoatwblr (reporter) - 2011-03-17 11:30 http://bugs.bacula.org/view.php?id=1704#c5804 ---------------------------------------------------------------------- I suspect you don't realise how much of a slowdown the current setup imposes - it's in the region of 50%. Additionally: When discussing things with Kern he specifically requested I file this kind of thing in Bugzilla so there is a record of it. ---------------------------------------------------------------------- (0006121) kern (administrator) - 2011-12-31 09:15 http://bugs.bacula.org/view.php?id=1704#c6121 ---------------------------------------------------------------------- Please re-open this bug or submit a new one if and when SEEK_HOLE and SEEK_DATA are implemented and released , because since that is a relatively simple means of finding holes that we might well implement it. Issue History Date Modified Username Field Change ====================================================================== 2011-03-08 17:36 stoatwblr New Issue 2011-03-17 10:19 ebollengier Note Added: 0005800 2011-03-17 10:19 ebollengier Status new => closed 2011-03-17 10:19 ebollengier Assigned To => ebollengier 2011-03-17 10:19 ebollengier Resolution open => no change required 2011-03-17 11:30 stoatwblr Note Added: 0005804 2011-03-17 11:30 stoatwblr Status closed => feedback 2011-03-17 11:30 stoatwblr Resolution no change required => reopened 2011-12-31 09:15 kern Note Added: 0006121 2011-12-31 09:15 kern Status feedback => closed 2011-12-31 09:15 kern Resolution reopened => no change required 2011-12-31 09:15 kern Description Updated 2011-12-31 09:15 kern Steps to Reproduce Updated ====================================================================== |