Re: [PATCH] block: kyber: make kyber more friendly with merging

Hi Jens and Holger

Thank for your kindly response.
That's really appreciated.

I will post next version based on Jens' patch.

Thanks
Jianchao

On 05/23/2018 02:32 AM, Holger Hoffstätte wrote:

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This looks great but prevents kyber from being built as module,
which is AFAIK supposed to work (and works now):

..
  CC [M]  block/kyber-iosched.o
  Building modules, stage 2.
  MODPOST 313 modules
ERROR: "bio_attempt_back_merge" [block/kyber-iosched.ko] undefined!
ERROR: "bio_attempt_front_merge" [block/kyber-iosched.ko] undefined!
ERROR: "bio_attempt_discard_merge" [block/kyber-iosched.ko] undefined!
ERROR: "blk_try_merge" [block/kyber-iosched.ko] undefined!
ERROR: "blk_rq_merge_ok" [block/kyber-iosched.ko] undefined!
..

It does build fine when compiled in, obviously. :)

It's basically duplicating the contents of blk_attempt_plug_merge().
I would suggest abstracting out the list loop and merge check
into a helper, that could then both be called from kyber and the
plug merge function.

See attached, prep patch and yours rebased on top of it.

That was quick. :)

Applies smoothly on top of my 4.16++ tree, now builds correctly as
module and is reproducibly (slightly) faster even on my pedestrian
SATA SSDs, now on par or occasionally even faster than mq-deadline.
What's not to like? So:

Tested-by: Holger Hoffstätte <redacted>