Re: [PATCH v2 1/4] blk-iocost: charge flushes as pageless random writes

[Christoph Hellwig]

On Sat, Sep 19, 2026 at 04:59:51AM -1000, Tejun Heo wrote:
> Hello, Tao.
> Pricing a flush as a random write, or as a page where that comes out to
> zero, is as arbitrary as pricing it at zero,

No, it absolutely is not.  For any flush that actually makes here it
is extremely expensive, and 0 is the wrongest possible value.  Even
batching does not change that, as batching is not actually effective
in any normal file system workload.