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On Tue, 2005-10-18 at 22:01 +0200, Guido Fiala wrote: > (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. Is there a reason why those applications couldn't use O_DIRECT ? Thanks, Badari - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.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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