OK, having fixed that issue, I'm faced with another one I don't know how to solve: I have my bcache set such that platters would be spun down most of the time if possible. writeback_delay is set to 6 hours, there's enough cache size, everything is set to hold data on the SSD as much as possible. However, my platters never spin down. iostat shows that there are some **zero-sized** writes to the backing device every 12 or so seconds on average (I ran iostat 600 to obtain those numbers). If I start dumping traffic, it's generated by bcache's kworker thread (identified by observing its activity while flushing dirty data). I have tried to modify parameters, but nothing I tried seemed to have any effect. Those writes are happening even if I reduce writeback_delay or any other parameter for that matter. They are not related to any actual writes to the bcache device (it doesn't matter whether I'm writing gigabytes or just doing minor iSCSI touches) Any suggestions highly appreciated, Jure On Sat, Dec 31, 2016 at 6:20 AM, Jure Erznožnik <jure.erznoznik@xxxxxxxxx> wrote: > This seems to have fixed that, thanks. I keep forgetting there's two > places I have to check for configuration. > > LP, > Jure > > On Fri, Dec 30, 2016 at 9:58 AM, Killian De Volder > <killian.de.volder@xxxxxxxxxxx> wrote: >> Also check congested_write_threshold_us, if the SSD is "congested" it bypasses it to speedup writes. >> >> Killian De Volder >> >> -- 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
