Re: Time sliced CFQ io scheduler

[Andrew Morton]

Jens Axboe <axboe@xxxxxxx> wrote:
>
> as:
> Reader: 27985KiB/sec (max_lat=34msec)
> Writer:    64KiB/sec (max_lat=1042msec)
> 
> cfq:
> Reader: 12703KiB/sec (max_lat=108msec)
> Writer:  9743KiB/sec (max_lat=89msec)
> 
> If you look at vmstat while running these tests, cfq and deadline give
> equal bandwidth for the reader and writer all the time, while as
> basically doesn't give anything to the writer (a single block per second
> only). Nick, is the write batching broken or something?

Looks like it.  We used to do 2/3rds-read, 1/3rd-write in that testcase.
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