# Inject I/O latency for RAID5/6 read and writes

- From: Alireza Haghdoost \<hidden\>
- Date: 2015-02-23 18:32:47 
- List: linux-raid
- Page: https://ratatoskr.run/linux-raid/2015/02/6629094
- Thread: https://ratatoskr.run/linux-raid/2015/02/6629094/t.md

```text
I needed to inject I/O completion latency in the RAID5/6 codes for
test purpose. I was wondering where would be the good place in
md/raid5.c code to add delay ?

So far I have tried adding mdelay/udelay in raid5_end_write_request()
and it seems it works to increase I/O completion of writes. However,
adding delay in raid5_end_read_request() does not really change the
read I/O latency. Any idea ?

--Alireza
```