On 2019/10/23 5:17 下午, Sergey Kolesnikov wrote: > ср, 23 окт. 2019 г. в 11:20, Coly Li <colyli@xxxxxxx>: >> >> On 2019/10/23 3:12 上午, Eric Wheeler wrote: > >>> On Tue, 15 Oct 2019, Coly Li wrote: >>>> I have no much idea. The 4Kn SSD is totally new to me. Last time I saw >>>> Eric Wheeler reported 4Kn hard diver didn't work well as backing device, >>>> and I don't find an exact reason up to now. I am not able to say 4Kn is >>>> not supported or not, before I have such device to test... > > Coly, thank you for your reply. It seems I'll have ot do some more > tests and dive a little into bcache sources when I have time. > Meanwhile, could you please explain what cache_bypass_misses and > cache_bypass_hits mean? It's not obvious from the docs. > > >> Yes, this is the problem I wanted to say. Kent suggested me to look into >> the extent code, but I didn't find anything suspicious. Also I tried to >> buy a 4Kn SSD, but it seemed not for consumer market and I could not >> find it from Taobao (www.taobao.com). > > I'm using SANDISK Extreme Pro SDSSDXPM2-500G-G25 M.2 NVMe drive and > it's quite common desktop drive, just use native 4K format (nvme-cli) > LBA Format 0 : Metadata Size: 0 bytes - Data Size: 512 bytes - > Relative Performance: 0x2 Good > LBA Format 1 : Metadata Size: 0 bytes - Data Size: 4096 bytes - > Relative Performance: 0x1 Better (in use) > > I'm not sure, but I think other drives support this too. Hi Sergey, Thanks for the hint, let me try on my NVMe SSD :-) -- Coly Li
