On 2022/03/29 22:41, Jens Axboe wrote:
On 3/29/22 8:40 AM, Christoph Hellwig wrote:
On Tue, Mar 29, 2022 at 08:35:29AM -0600, Jens Axboe wrote:
But more importantly why does your use case even have splits that get
submitted together? Is this a case of Linus' stupidly low default
max_sectors when the hardware supports more, or is the hardware limited
to a low number of sectors per request? Or do we hit another reason
for the split?
See the posted use case, it's running 512kb ios on a 128kb device.
Hi,
The problem was first found during kernel upgrade(v3.10 to v4.18), and
we maintain a series of io performance test suites, and one of the test
is fio random rw with large bs. In the environment, the 'max_sectors_kb'
is 256kb, and fio bs is 1m.
That is an awfully low limit these days. I'm really not sure we should
optimize the block layer for that.
That's exactly what my replies have been saying. I don't think this is
a relevant thing to optimize for.
If the use case that large ios get submitted together is not a common
issue（probably not since it's been a long time without complaining),
I agree that we should not optimize the block layer for that.
Thanks,
Kuai
Fixing fairness for wakeups seems useful, however.
