Re: [BENCHMARK] 2.4.{18,19{-ck9},20rc1{-aa1}} with contest

[Andrew Morton]

Andrea Arcangeli wrote:
> 
> > Whether the IO is synchronous or asynchronous shouldn't matter much,
> 
> the fact the I/O is sync or async makes the whole difference. with sync
> reads the vmstat line in the read column will be always very small
> compared to the write column under a write flood. This can be fixed either:
> 
> 1) with hacks in the elevator ala read-latency that are not generic and
>    could decrease performance of other workloads

read-latency will only do the front-insertion if it was unable to find a
merge or insert on the tail-to-head search.

And the problem it desparately addresses is severe.