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ZiyangZhang authored
UBLK_IO_NEED_GET_DATA is one ublk IO command. It is designed for a user application who wants to allocate IO buffer and set IO buffer address only after it receives an IO request from ublksrv. This is a reasonable scenario because these users may use a RPC framework as one IO backend to handle IO requests passed from ublksrv. And a RPC framework may allocate its own buffer(or memory pool). This new feature (UBLK_F_NEED_GET_DATA) is optional for ublk users. Related userspace code has been added in ublksrv[1] as one pull request. Test cases for this feature are added in ublksrv and all the tests pass. The performance result shows that this new feature does bring additional latency because one IO is issued back to ublk_drv once again to copy data from bio vectors to user-provided data buffer. UBLK_IO_NEED_GET_DATA is suitable for bigger block size such as 512B or 1MB. [1] https://github.com/ming1/ubdsrvSigned-off-by:
ZiyangZhang <ZiyangZhang@linux.alibaba.com> Reviewed-by:
Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/3a21007ea1be8304246e654cebbd581ab0012623.1659011443.git.ZiyangZhang@linux.alibaba.comSigned-off-by:
Jens Axboe <axboe@kernel.dk>
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