Re: Expense of read_iter

[Mikulas Patocka]

On Tue, 12 Jan 2021, Zhongwei Cai wrote:

> 
> I'm working with Mingkai on optimizations for Ext4-dax.

What specific patch are you working on? Please, post it somewhere.

> We think that optmizing the read-iter method cannot achieve the
> same performance as the read method for Ext4-dax. 
> We tried Mikulas's benchmark on Ext4-dax. The overall time and perf
> results are listed below:
> 
> Overall time of 2^26 4KB read.
> 
> Method       Time
> read         26.782s
> read-iter    36.477s

What happens if you use this trick ( https://lkml.org/lkml/2021/1/11/1612 )
- detect in the "read_iter" method that there is just one segment and 
treat it like a "read" method. I think that it should improve performance 
for your case.

Mikulas