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gfiala at s Oct 18, 2005, 1:01 PM Views: 1505 Permalink large files unnecessary trashing filesystem cache? (please note, i'am not subscribed to the list, please CC me on reply) Story: Once in while we have a discussion at the vdr (video disk recorder) mailing list about very large files trashing the filesystems memory cache leading to unnecessary delays accessing directory contents no longer cached. This program and certainly all applications that deal with very large files only read once (much larger than usual memory) - it happens that all other cached blocks of the filessystem are removed from memory solely to keep as much as possible of that file in memory, which seems to be a bad strategy in most situations. Of course one could always implement f_advise-calls in all applications, but i suggest a discussion if a maximum (configurable) in-memory-cache on a per-file base should be implemented in linux/mm or where this belongs. My guess was, it has something to do with mm/readahead.c, a test limiting the result of the function "max_sane_readahead(...) to 8 MBytes as a quick and dirty test did not solve the issue, but i might have done something wrong. I've searched the archive but could not find a previous discussion - is this a new idea? It would be interesting to discuss if and when this proposed feature could lead to better performance or has any unwanted side effects. Thanks for ideas on that issue. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo[at]vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/

Subject User Time large files unnecessary trashing filesystem cache? gfiala at s Oct 18, 2005, 1:01 PM     Re: large files unnecessary trashing filesystem cache? pbadari at gmail Oct 18, 2005, 1:48 PM         Re: large files unnecessary trashing filesystem cache? gfiala at s Oct 20, 2005, 8:23 AM     Re: large files unnecessary trashing filesystem cache? harvested.in.lkml at posting Oct 18, 2005, 2:58 PM         Re: large files unnecessary trashing filesystem cache? pbadari at gmail Oct 18, 2005, 4:05 PM             Re: large files unnecessary trashing filesystem cache? david.lang at digitalinsight Oct 18, 2005, 5:20 PM             Re: large files unnecessary trashing filesystem cache? fawadlateef at gmail Oct 18, 2005, 5:33 PM             Re: large files unnecessary trashing filesystem cache? 7eggert at gmx Oct 19, 2005, 12:23 AM                 Re: large files unnecessary trashing filesystem cache? gfiala at s Oct 19, 2005, 4:06 AM         Re: large files unnecessary trashing filesystem cache? avi at argo Oct 19, 2005, 6:43 AM     Re: large files unnecessary trashing filesystem cache? ecki at lina Oct 18, 2005, 6:42 PM     Re: large files unnecessary trashing filesystem cache? andrew.j.wade at gmail Oct 18, 2005, 8:02 PM     Re: large files unnecessary trashing filesystem cache? rlrevell at joe-job Oct 18, 2005, 9:10 PM         Re: large files unnecessary trashing filesystem cache? pbadari at gmail Oct 19, 2005, 8:43 AM         Re: large files unnecessary trashing filesystem cache? gfiala at s Oct 19, 2005, 10:58 AM             Re: large files unnecessary trashing filesystem cache? mrmacman_g4 at mac Oct 19, 2005, 11:43 AM                 Re: large files unnecessary trashing filesystem cache? gfiala at s Oct 19, 2005, 11:52 AM     Re: large files unnecessary trashing filesystem cache? akpm at osdl Oct 18, 2005, 9:37 PM         Re: large files unnecessary trashing filesystem cache? andrew.j.wade at gmail Oct 18, 2005, 10:45 PM         Re: large files unnecessary trashing filesystem cache? gfiala at s Oct 19, 2005, 4:10 AM             Re: large files unnecessary trashing filesystem cache? ioe-lkml at rameria Oct 19, 2005, 8:54 AM                 Re: large files unnecessary trashing filesystem cache? akpm at osdl Oct 19, 2005, 12:49 PM                     Re: large files unnecessary trashing filesystem cache? pj at sgi Oct 19, 2005, 3:26 PM                     Re: large files unnecessary trashing filesystem cache? ioe-lkml at rameria Oct 19, 2005, 11:28 PM     Re: large files unnecessary trashing filesystem cache? gfiala at s Oct 19, 2005, 4:01 AM

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