Rather than aggregate the completion list into an intermediate vector
instead adjust the API to provide one completion item at a time.
With DHAT this shows the number of heap allocations has decreased.
Before:
dhat: Total: 623,852 bytes in 8,157 blocks
After:
dhat: Total: 380,444 bytes in 3,469 blocks
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Rather than passing the vector of iovecs for the I/O to act on pass a
reference to the slice of values inside them. This removes the explicit
container type from the API allowing the use of e.g. SmallVec.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
When using DHAT[1] for analysis the amount heap allocations change from:
dhat: Total: 3,186,536 bytes in 41,452 blocks
to
dhat: Total: 1,059,816 bytes in 34,747 blocks
When running against virtio-block; this still more allocations than
virtio-pmem but a significant improvement without any cost.
[1] https://docs.rs/dhat/latest/dhat/
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
