The parameter allows to specify what granularity is used in
data area provided via uio device. Data space now appears to
userspace as chunks of data_pages_per_blk * PAGE_SIZE.
If the default value 1 of data_pages_per_blk is not changed,
tcmu behaves like unchanged.
Setting data_pages_per_blk > 1 allows tcmu to allocate less
but bigger chunks, which makes allocation quicker. Also
userspace will see less iovecs per data transfer. If chunk
size is as big as biggest possible data transfer, userspace
will see consecutive buffers only.
Starting from kernel 5.13 tcmu (user based backend) supports config parameter DataPagesPerBlk alias data_pages_per_blk.
This change enables rtslib to save the new config parameter to saveconfig.json.
Signed-off-by: Bodo Stroesser bostroesser@gmail.com
Short explanation of the new tcmu config param:
The parameter allows to specify what granularity is used in data area provided via uio device. Data space now appears to userspace as chunks of data_pages_per_blk * PAGE_SIZE. If the default value 1 of data_pages_per_blk is not changed, tcmu behaves like unchanged.
Setting data_pages_per_blk > 1 allows tcmu to allocate less but bigger chunks, which makes allocation quicker. Also userspace will see less iovecs per data transfer. If chunk size is as big as biggest possible data transfer, userspace will see consecutive buffers only.