> I assume compressed blocks can be larger than PAGE_CACHE_SIZE? This suffers > from the rather obvious inefficiency that you decompress a big block > > PAGE_CACHE_SIZE, but only copy one PAGE_CACHE_SIZE page out of it. If > multiple files are being read simultaneously (a common occurrence), then > each is going to replace your one cached uncompressed block > (sbi->current_cnode_index), leading to decompressing the same blocks over > and over again on sequential file access. > > readpage file A, index 1 -> decompress block X > readpage file B, index 1 -> decompress block Y (replaces X) > readpage file A, index 2 -> repeated decompress of block X (replaces Y) > readpage file B, index 2 -> repeated decompress of block Y (replaces X) > > and so on. Yep. Been thinking about optimizing it. So far it hasn't been an issue for my customers. Most fs traffic being on the XIP pages. Once I get a good automated performance test up we'll probably look into something to improve this. -- To unsubscribe from this list: send the line "unsubscribe linux-embedded" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
