Hi Kent, I am trying to configure the cache to always cache. The only time I want it to bypass the cache is when it has to. (ie.. cache full) In particular - I want all writes to hit the writeback cache and never be written directly. (Unless no space is left for writeback) I am not sure how to configure this. I thought I had done it once before but I cant seem to reproduce it. Here are my settings so far: /sys/block/bcache0/bcache/ cache_mode = writethrough [writeback] writearound none readahead = 0 running = 1 sequential_cutoff = 0 (also tried this at 1.1G, which appears to be maximum) sequential_merge = 1 (also tried 0. I have no idea what this means) state = clean writeback_delay = 30 writeback_metadata = 1 (not sure what this does) writeback_percent = 40 (also tried at 10) writeback_running = 1 not sure what else there is to configure. Any suggestions would be appreciated. I am basically trying to maintain responsive disk access as much as possible. The backing storage is on a slow link to a SAN and when accessed directly is relatively slow. I want it to use the cache as much as is possible and then bCache write the cache data to the backend storage behind the scenes. Workload is mixed.. random and sequential reads and writes, anything from just a few bytes to 4-5Gb files. I am guessing that sequential_cutoff = 0 disables the cut-off feature. (I tried the max of 1.1G too, just in case) I am using nmon to monitor where data is being written while copying /usr into the filesystem on cache0p1. (ext4) I am seeing writes going to the cache device and the backing device simultaneously - but the cache is not written to heavily. Performance seen when copying is similar to that of if I was just writing to the backing device directly. (maybe a little better since some bits are getting written to the cache) Any suggestion what I may be doing wrong? Cheers, James -- To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
