Re: [PATCH v6 4/5] 9pfs: T_readdir latency optimization

[Christian Schoenebeck]

On Sonntag, 19. April 2020 17:06:17 CEST Christian Schoenebeck wrote:
> Make top half really top half and bottom half really bottom half:
> 
> Each T_readdir request handling is hopping between threads (main
> I/O thread and background I/O driver threads) several times for
> every individual directory entry, which sums up to huge latencies
> for handling just a single T_readdir request.
> 
> Instead of doing that, collect now all required directory entries
> (including all potentially required stat buffers for each entry) in
> one rush on a background I/O thread from fs driver by calling the
> previously added function v9fs_co_readdir_many() instead of
> v9fs_co_readdir(), then assemble the entire resulting network
> response message for the readdir request on main I/O thread. The
> fs driver is still aborting the directory entry retrieval loop
> (on the background I/O thread inside of v9fs_co_readdir_many())
> as soon as it would exceed the client's requested maximum R_readdir
> response size. So this will not introduce a performance penalty on
> another end.
> 
> Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
> ---
>  hw/9pfs/9p.c | 122 +++++++++++++++++++++++----------------------------
>  1 file changed, 55 insertions(+), 67 deletions(-)

Ping. Anybody?

I would like to roll out this patch set soon and this is the only patch in 
this series missing a review yet.