[ceph-users] Re: RBD with PWL cache shows poor performance compared to cache device

On Tue, Jun 27, 2023 at 11:50 AM Matthew Booth <mbooth@redhat.com> wrote:

What do you mean by saturated here? FWIW I was using the default cache size of 1G and each test run only wrote ~100MB of data, so I don't think I ever filled the cache, even with multiple runs.

Ah, my apologies - I saw that fio had been invoked in time-based mode and assumed it was exceeding the pwl size, but doing the math on the latency and block size, you should be fine. You're right, I wouldn't expect that you would be filling the pwl cache, and thus the results you are getting are Not Good(tm). Josh