Re: [PATCH] FUSE: Improve aio directIO write performance for size extending writes.

[Ashish Sangwan]

Hi Miklos,

Did you get any time to look into the patch?
Its been more than two months.

On Thu, Apr 14, 2016 at 6:02 PM, Ashish Sangwan
<ashishsangwan2@xxxxxxxxx> wrote:
> *ping*
>
> Last time it bounced off the fuse mailing list.
>
> On Thu, Apr 7, 2016 at 5:18 PM, Ashish Sangwan <ashishsangwan2@xxxxxxxxx> wrote:
>> While sending the blocking directIO in fuse, the write request is broken
>> into sub-requests, each of default size 128k and all the requests are sent
>> in non-blocking background mode if async_dio mode is supported by libfuse.
>> The process which issue the write wait for the completion of all the
>> sub-requests. Sending multiple requests parallely gives a chance to perform
>> parallel writes in the user space fuse implementation if it is
>> multi-threaded and hence improves the performance.
>>
>> When there is a size extending aio dio write, we switch to
>> blocking mode so that we can properly update the size of the file after
>> completion of the writes. However, in this situation all the sub-requests
>> are sent in serialized manner where the next request is sent only after
>> receiving the reply of the current request. Hence the multi-threaded user
>> space implementation is not utilized properly.
>>
>> This patch changes the size extending aio dio behavior to exactly follow
>> blocking dio. For multi threaded fuse implementation having 10 threads and
>> using buffer size of 64MB to perform async directIO, we are getting double
>> the speed.
>>
>> Signed-off-by: Ashish Sangwan <ashishsangwan2@xxxxxxxxx>
>> ---
>>  fs/fuse/file.c   |   16 ++++++++--------
>>  fs/fuse/fuse_i.h |    1 +
>>  2 files changed, 9 insertions(+), 8 deletions(-)
>>
>> diff --git a/fs/fuse/file.c b/fs/fuse/file.c
>> index 9dde38f..b4f8b83 100644
>> --- a/fs/fuse/file.c
>> +++ b/fs/fuse/file.c
>> @@ -572,11 +572,11 @@ static void fuse_aio_complete(struct fuse_io_priv *io, int err, ssize_t pos)
>>                 io->bytes = pos;
>>
>>         left = --io->reqs;
>> -       if (!left && is_sync)
>> +       if (!left && (is_sync || io->blocking_aio))
>>                 complete(io->done);
>>         spin_unlock(&io->lock);
>>
>> -       if (!left && !is_sync) {
>> +       if (!left && !is_sync && !io->blocking_aio) {
>>                 ssize_t res = fuse_get_res_by_io(io);
>>
>>                 if (res >= 0) {
>> @@ -2884,17 +2884,17 @@ fuse_direct_IO(struct kiocb *iocb, struct iov_iter *iter, loff_t offset)
>>          */
>>         io->async = async_dio;
>>         io->iocb = iocb;
>> +       io->blocking_aio = false;
>>
>>         /*
>> -        * We cannot asynchronously extend the size of a file. We have no method
>> -        * to wait on real async I/O requests, so we must submit this request
>> -        * synchronously.
>> +        * We cannot asynchronously extend the size of a file.
>> +        * In such case the aio will behave exactly like sync io.
>>          */
>>         if (!is_sync && (offset + count > i_size) &&
>>             iov_iter_rw(iter) == WRITE)
>> -               io->async = false;
>> +               io->blocking_aio = true;
>>
>> -       if (io->async && is_sync) {
>> +       if (io->async && (is_sync | io->blocking_aio)) {
>>                 /*
>>                  * Additional reference to keep io around after
>>                  * calling fuse_aio_complete()
>> @@ -2914,7 +2914,7 @@ fuse_direct_IO(struct kiocb *iocb, struct iov_iter *iter, loff_t offset)
>>                 fuse_aio_complete(io, ret < 0 ? ret : 0, -1);
>>
>>                 /* we have a non-extending, async request, so return */
>> -               if (!is_sync)
>> +               if (!is_sync && !io->blocking_aio)
>>                         return -EIOCBQUEUED;
>>
>>                 wait_for_completion(&wait);
>> diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
>> index eddbe02..a7cf03f 100644
>> --- a/fs/fuse/fuse_i.h
>> +++ b/fs/fuse/fuse_i.h
>> @@ -256,6 +256,7 @@ struct fuse_io_priv {
>>         struct kiocb *iocb;
>>         struct file *file;
>>         struct completion *done;
>> +       bool blocking_aio;
>>  };
>>
>>  #define FUSE_IO_PRIV_SYNC(f) \
>> --
>> 1.7.9.5
>>