io_uring/rw: always setup io_async_rw for read/write requests

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read/write requests try to put everything on the stack, and then alloc
and copy if a retry is needed. This necessitates a bunch of nasty code
that deals with intermediate state.

Get rid of this, and have the prep side setup everything that is needed
upfront, which greatly simplifies the opcode handlers.

This includes adding an alloc cache for io_async_rw, to make it cheap
to handle.

In terms of cost, this should be basically free and transparent. For
the worst case of {READ,WRITE}_FIXED which didn't need it before,
performance is unaffected in the normal peak workload that is being
used to test that. Still runs at 122M IOPS.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

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This commit is contained in:

Jens Axboe 2024-03-18 16:13:01 -06:00

parent d80f940701

commit a9165b83c1

5 changed files with 278 additions and 298 deletions

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1

include/linux/io_uring_types.h

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3

io_uring/io_uring.c

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15

io_uring/opdef.c

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548

io_uring/rw.c

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19

io_uring/rw.h

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