On Sat, Nov 3, 2012 at 4:22 PM, James Sefton <james@xxxxxxxxxxxx> wrote: > Aha, > > Setting mode to writethrough does cause all writes to be written to both cache and backing disk simultaneously - so not what I was looking for. > > However, it seems the congestion option is what I was looking for. > > Setting cache_mode to writeback and then setting both congested_[read/write]_threshold_us to 0 as you directed seems to do pretty much exactly what I want. (at least it appears that almost all writes are going to cache first and then starts sending the data to the backing store about 30 seconds later as expected) > > Perfect, thank-you. > > Any chance you could briefly explain what the two congestion values do? They're for when your cache device is slower than your backing device(s) - to prevent the cache device from being a bottleneck, it starts cranking down the bypass threshold when latency to the SSD goes over that threshold -- 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
