Re: [PATCH 13/15] fuse: Process requests in coroutines

[Stefan Hajnoczi <stefanha@redhat.com>]

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On Tue, Mar 25, 2025 at 05:06:53PM +0100, Hanna Czenczek wrote:
> Make fuse_process_request() a coroutine_fn (fuse_co_process_request())
> and have read_from_fuse_fd() launch it inside of a newly created
> coroutine instead of running it synchronously.  This way, we can process
> requests in parallel.
> 
> These are the benchmark results, compared to (a) the original results
> with libfuse, and (b) the results after switching away from libfuse
> (i.e. before this patch):
> 
> file:                  (vs. libfuse / vs. no libfuse)
>   read:
>     seq aio:   120.6k ±1.1k (+ 53 % / + 58 %)
>     rand aio:  113.3k ±5.9k (+188 % / +325 %)
>     seq sync:   52.4k ±0.4k (+ 61 % / + 10 %)
>     rand sync:  10.4k ±0.4k (+  6 % / +  3 %)
>   write:
>     seq aio:    79.8k ±0.8k (+ 29 % / + 37 %)
>     rand aio:   79.0k ±0.6k (+ 29 % / + 36 %)
>     seq sync:   41.5k ±0.3k (+ 49 % / + 15 %)
>     rand sync:  41.4k ±0.2k (+ 50 % / + 15 %)
> null:
>   read:
>     seq aio:   266.1k ±1.5k (+ 24 % / -  1 %)
>     rand aio:  264.1k ±2.5k (+ 24 % / ±  0 %)
>     seq sync:  135.6k ±3.2k (+ 50 % / +  1 %)
>     rand sync: 134.7k ±3.0k (+ 50 % / +  2 %)
>   write:
>     seq aio:   281.0k ±1.8k (+ 38 % / +  2 %)
>     rand aio:  288.1k ±6.1k (+ 43 % / +  6 %)
>     seq sync:  142.2k ±3.1k (+ 65 % / +  9 %)
>     rand sync: 141.1k ±2.9k (+ 66 % / + 11 %)
> 
> So for non-AIO cases (and the null driver, which does not yield), there
> is little change; but for file AIO, results greatly improve, resolving
> the performance issue we saw before (when switching away from libfuse).
> 
> Signed-off-by: Hanna Czenczek <hreitz@redhat.com>
> ---
>  block/export/fuse.c | 209 ++++++++++++++++++++++++++------------------
>  1 file changed, 126 insertions(+), 83 deletions(-)

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

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