linux-kernel - Re: [PATCH 7/9] io-wq: implement fixed worker logic

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Date:   Sat, 30 Apr 2022 07:27:13 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     Hao Xu <haoxu.linux@...il.com>, io-uring@...r.kernel.org
Cc:     Pavel Begunkov <asml.silence@...il.com>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 7/9] io-wq: implement fixed worker logic

On 4/29/22 4:18 AM, Hao Xu wrote:
> @@ -1030,6 +1101,7 @@ static bool io_wq_work_match_item(struct io_wq_work *work, void *data)
>  static void io_wqe_enqueue(struct io_wqe *wqe, struct io_wq_work *work)
>  {
>  	struct io_wqe_acct *acct = io_work_get_acct(wqe, work);
> +	struct io_wqe_acct *fixed_acct;
>  	struct io_cb_cancel_data match;
>  	unsigned work_flags = work->flags;
>  	bool do_create;
> @@ -1044,8 +1116,14 @@ static void io_wqe_enqueue(struct io_wqe *wqe, struct io_wq_work *work)
>  		return;
>  	}
>  
> +	fixed_acct = io_get_acct(wqe, !acct->index, true);
> +	if (fixed_acct->fixed_worker_registered && !io_wq_is_hashed(work)) {
> +		if (io_wqe_insert_private_work(wqe, work, fixed_acct))
> +			return;
> +	}
> +

As per previous email, I was going to comment back saying "why don't we
just always do hashed work on the non-fixed workers?" - but that's
already what you are doing. Isn't this fine, does anything else need to
get done here in terms of hashed work and fixed workers? If you need
per-iowq serialization, then you don't get a fixed worker.

-- 
Jens Axboe