Write to L2 Cache immediately
Posted: Sat Sep 16, 2023 4:42 pm
Currently the software will wait for an idle period before it starts writing to the L2 cache. When it decides to do so it must then re-read the contents that should be cached so it can write it to the L2.
This means a busy disk will almost never receive the benefit! In fact a busy disk will be slower due to primocache.
Currently my system has been up 25 minutes, it has read 14GB from the HDD. So far it has only written 11MB to the cache! Such a tiny percentage.
Why instead can it not write to the L2 instantly (which a gather interval of instant suggests but it is clearly not true). An instant write would mean we don't need to go and read the data again some time later, the cache will warm faster, benefit comes in instantly, and there is no slowdown from an additional read.
This means a busy disk will almost never receive the benefit! In fact a busy disk will be slower due to primocache.
Currently my system has been up 25 minutes, it has read 14GB from the HDD. So far it has only written 11MB to the cache! Such a tiny percentage.
Why instead can it not write to the L2 instantly (which a gather interval of instant suggests but it is clearly not true). An instant write would mean we don't need to go and read the data again some time later, the cache will warm faster, benefit comes in instantly, and there is no slowdown from an additional read.