On Thu, Oct 5, 2017 at 10:38 AM, Coly Li <[email protected]> wrote: > [snip] > In this test, without bio reorder patches, writeback throughput is > much faster, you may see the write request number and request merge > number are also much faster then bio reorder patches. After around 10 > minutes later, there is no obvious performance difference with/without > the bio reorder patches. Therefore in this test, with bio reorder > patches, I observe a worse writeback performance result. > > The above tests tell me, to get a better writeback performance with bio > reorder patches, a specific situation is required (many contiguous dirty > data on cache device), this situation can only happen in some specific > of work loads. In general writeback situations, reordering bios by > waiting does not have significant performance advantage, and even > performance regression is observed.
I mean, did you not notice that one of the changes is to limit the amount of write-issue-merge from the current behavior? It's not exactly surprising that the initial/peak rate is a bit lower initially... Your test methodology is flawed-- I tried telling you this from the beginning-- and I'm not convinced at all you understand the point of the patches. But hey, there's not really any other reviewers on bcache stuff, so I guess my stuff is blocked forever. ;) Mike
