Hi,
On 2020-02-14 13:13:35 -0700, Jens Axboe wrote:
> On 2/14/20 12:50 PM, Andres Freund wrote:
> > which I think is pretty clear evidence we're hitting fairly significant
> > contention on the queue lock.
> >
> >
> > I am hitting this in postgres originally, not fio, but I thought it's
> > easier to reproduce this way. There's obviously benefit to doing things
> > in the background - but it requires odd logic around deciding when to
> > use io_uring, and when not.
> >
> > To be clear, none of this happens with DIO, but I don't forsee switching
> > to DIO for all IO by default ever (too high demands on accurate
> > configuration).
>
> Can you try with this added?
>
>
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index 76cbf474c184..207daf83f209 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -620,6 +620,7 @@ static const struct io_op_def io_op_defs[] = {
> .async_ctx = 1,
> .needs_mm = 1,
> .needs_file = 1,
> + .hash_reg_file = 1,
> .unbound_nonreg_file = 1,
> },
> [IORING_OP_WRITEV] = {
> @@ -634,6 +635,7 @@ static const struct io_op_def io_op_defs[] = {
> },
> [IORING_OP_READ_FIXED] = {
> .needs_file = 1,
> + .hash_reg_file = 1,
> .unbound_nonreg_file = 1,
> },
> [IORING_OP_WRITE_FIXED] = {
> @@ -711,11 +713,13 @@ static const struct io_op_def io_op_defs[] = {
> [IORING_OP_READ] = {
> .needs_mm = 1,
> .needs_file = 1,
> + .hash_reg_file = 1,
> .unbound_nonreg_file = 1,
> },
> [IORING_OP_WRITE] = {
> .needs_mm = 1,
> .needs_file = 1,
> + .hash_reg_file = 1,
> .unbound_nonreg_file = 1,
> },
> [IORING_OP_FADVISE] = {
> @@ -955,7 +959,7 @@ static inline bool io_prep_async_work(struct io_kiocb *req,
> bool do_hashed = false;
>
> if (req->flags & REQ_F_ISREG) {
> - if (def->hash_reg_file)
> + if (!(req->kiocb->ki_flags & IOCB_DIRECT) && def->hash_reg_file)
> do_hashed = true;
> } else {
> if (def->unbound_nonreg_file)
I can (will do Sunday, on the road till then). But I'm a bit doubtful
it'll help. This is using WRITEV after all, and I only see a single
worker?
Greetings,
Andres Freund
