Re: [RFC] fuse: fuse support zero copy.

[Jens Axboe <axboe@kernel.dk>]

On 10/20/25 2:00 AM, Xiaobing Li wrote:
> DDN has enabled Fuse to support the io-uring solution, allowing us 
> to implement zero copy on this basis to further improve performance.
> 
> We have currently implemented zero copy using io-uring's fixed-buf 
> feature, further improving Fuse read performance. The general idea is 
> to first register a shared memory space through io_uring. 
> Then, libfuse in user space directly stores the read data into 
> the registered memory. The kernel then uses the io_uring_cmd_import_fixed 
> interface to directly retrieve the read results from the 
> shared memory, eliminating the need to copy data from user space to 
> kernel space.
> 
> The test data is as follows:
> 
> 4K IO size                                                           gain
> -------------------------------------------------------------------------
>                                |   no zero copy   |    zero copy  |  
> rw         iodepth     numjobs |      IOPS        |      IOPS     |    
> read          1           1    |      93K         |      97K      |  1.04
> read          16          16   |      169K        |      172K     |  1.02
> read          16          32   |      172K        |      173K     |  1.01
> read          32          16   |      169K        |      171K     |  1.01
> read          32          32   |      172K        |      173K     |  1.01
> randread      1           1    |      116K        |      136K     |  1.17
> randread      1           32   |      985K        |      994K     |  1.01
> randread      64          1    |      234K        |      261K     |  1.12
> randread      64          16   |      166K        |      168K     |  1.01
> randread      64          32   |      168K        |      170K     |  1.01
> 
> 128K IO size                                                         gain
> -------------------------------------------------------------------------
>                                |   no zero copy   |    zero copy  |
> rw         iodepth     numjobs |      IOPS        |      IOPS     |  
> read           1          1    |      24K         |      28K      |  1.17
> read           16         1    |      17K         |      19K      |  1.12
> read           64         1    |      17K         |      19K      |  1.12
> read           64         16   |      51K         |      55K      |  1.08
> read           64         32   |      54K         |      56K      |  1.04
> randread       1          1    |      24K         |      25K      |  1.04
> randread       16         1    |      17K         |      19K      |  1.12
> randread       64         1    |      16K         |      19K      |  1.19
> randread       64         16   |      50K         |      54K      |  1.08
> randread       64         32   |      49K         |      55K      |  1.12
> -------------------------------------------------------------------------
> 
> I will list the code after this solution is confirmed to be feasible.

Can you post the patches? A bit hard to tell if something is feasible or
the right direction without them :-)

-- 
Jens Axboe