On Tue, 2017-05-02 at 21:06 -0500, Mike Christie wrote: > On 05/02/2017 02:54 AM, lixiubo@xxxxxxxxxxxxxxxxxxxx wrote: > > From: Xiubo Li <lixiubo@xxxxxxxxxxxxxxxxxxxx> > > > > For the "struct tcmu_cmd_entry" in cmd area, the minimum size > > will be sizeof(struct tcmu_cmd_entry) == 112 Bytes. And it could > > fill about (sizeof(struct rsp) - sizeof(struct req)) / > > sizeof(struct iovec) == 68 / 16 ~= 4 data regions(iov[4]) by > > default. > > > > For most tcmu_cmds, the data block indexes allocated from the > > data area will be continuous. And for the continuous blocks they > > will be merged into the same region using only one iovec. For > > the current code, it will always allocates the same number of > > iovecs with blocks for each tcmu_cmd, and it will wastes much > > memories. > > > > For example, when the block size is 4K and the DATA_OUT buffer > > size is 64K, and the regions needed is less than 5(on my > > environment is almost 99.7%). The current code will allocate > > about 16 iovecs, and there will be (16 - 4) * sizeof(struct > > iovec) = 192 Bytes cmd area memories wasted. > > > > Here adds two helpers to calculate the base size and full size > > of the tcmu_cmd. And will recalculate them again when it make sure > > how many iovs is needed before insert it to cmd area. > > > > Signed-off-by: Xiubo Li <lixiubo@xxxxxxxxxxxxxxxxxxxx> > > Looks ok to me. Thanks. > > Acked-by: Mike Christie <mchristi@xxxxxxxxxx> Applied. Thanks Xiubo + MNC.
