From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta-64-227.siemens.flowmailer.net (mta-64-227.siemens.flowmailer.net [185.136.64.227]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2300E1C9DFA for ; Fri, 6 Sep 2024 09:53:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.136.64.227 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725616427; cv=none; b=bw0crbEYVb+3U9UXEw2ygyrPm3I1tOGN2Uf6dMV/nfVtlMyNIAPEhfSEhfbgQ2RSVbikvWtWJ3HCDxLors8S+E8jEBGamZ7C0189Wrsl7609FZjC0Ly3j6hVY3e7PEbhh8b3gtqUTROLMFXYuHHy9WLcatealUYKF8K1rcbAGyU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725616427; c=relaxed/simple; bh=8XHNoIQfIyQtbDLRSGDPf+aLvqEvZjnzaj5Dek7I8Q4=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=cjgwETmB4aExo3uutxeQMIkIc3k7Fv8GjgWe9j/aG5Nhyhn573kAbFNvJHHZip7po12FG9oZWNOWP3xhNhKDdXQTFO4pbKuMi8O8/S4NcjZiA7gnUZAFPKI0sBoWoqMaDz8wmDVXNeBEII3fLgLYFZBVNXbJ03VHmoY738qu+WU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=siemens.com; spf=pass smtp.mailfrom=rts-flowmailer.siemens.com; dkim=pass (2048-bit key) header.d=siemens.com header.i=felix.moessbauer@siemens.com header.b=UMsxOR18; arc=none smtp.client-ip=185.136.64.227 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=siemens.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=rts-flowmailer.siemens.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=siemens.com header.i=felix.moessbauer@siemens.com header.b="UMsxOR18" Received: by mta-64-227.siemens.flowmailer.net with ESMTPSA id 2024090609533917b4daed5334c1e57b for ; Fri, 06 Sep 2024 11:53:40 +0200 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; s=fm1; d=siemens.com; i=felix.moessbauer@siemens.com; h=Date:From:Subject:To:Message-ID:MIME-Version:Content-Type:Content-Transfer-Encoding:Cc:References:In-Reply-To; bh=ghovqhbYJ+w5KNxfwKu3pn/axYB+6/3jSM34AUo5pxQ=; b=UMsxOR18TiuVRFfTwYuCaGJ0NWLsRHYIYHuNNvZYBdXXQhvGSKIMyzV2bZAEFkeT/K3gEI h6Yg+ZBNRWmyiN5zzinjxeJ/EccL9MAFnkL5bZUgw5NY4NLB6CFNsCMBfJK7fbptc71PGEsR S8iTryuHtde5i9HgG6MU/xjmWXytJs5jQKHy5DBIVf9AbVWUcYb0fDDAftpgkDA4qnDrPXE9 uzzB1Sj07lz1gjjo/Ucp0s5ABkOAEZlE+6vLJnYlQQz5COZoHgFKfJzFd/Yf6MpvorPXOasF yh6jAk/FD4a63ZiCl08ye2xHG0OI7Pu1yQK9IhpFayeXx+6ToTzdEMRA==; From: Felix Moessbauer To: stable@vger.kernel.org Cc: io-uring@vger.kernel.org, cgroups@vger.kernel.org, axboe@kernel.dk, asml.silence@gmail.com, dqminh@cloudflare.com, longman@redhat.com, adriaan.schmidt@siemens.com, florian.bezdeka@siemens.com, Felix Moessbauer Subject: [PATCH][6.1][1/2] io_uring/io-wq: stop setting PF_NO_SETAFFINITY on io-wq workers Date: Fri, 6 Sep 2024 11:53:20 +0200 Message-Id: <20240906095321.388613-2-felix.moessbauer@siemens.com> In-Reply-To: <20240906095321.388613-1-felix.moessbauer@siemens.com> References: <20240906095321.388613-1-felix.moessbauer@siemens.com> Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Flowmailer-Platform: Siemens Feedback-ID: 519:519-1321639:519-21489:flowmailer From: Jens Axboe commit 01e68ce08a30db3d842ce7a55f7f6e0474a55f9a upstream. Every now and then reports come in that are puzzled on why changing affinity on the io-wq workers fails with EINVAL. This happens because they set PF_NO_SETAFFINITY as part of their creation, as io-wq organizes workers into groups based on what CPU they are running on. However, this is purely an optimization and not a functional requirement. We can allow setting affinity, and just lazily update our worker to wqe mappings. If a given io-wq thread times out, it normally exits if there's no more work to do. The exception is if it's the last worker available. For the timeout case, check the affinity of the worker against group mask and exit even if it's the last worker. New workers should be created with the right mask and in the right location. Reported-by:Daniel Dao Link: https://lore.kernel.org/io-uring/CA+wXwBQwgxB3_UphSny-yAP5b26meeOu1W4TwYVcD_+5gOhvPw@mail.gmail.com/ Signed-off-by: Jens Axboe Signed-off-by: Felix Moessbauer --- io_uring/io-wq.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/io_uring/io-wq.c b/io_uring/io-wq.c index 04503118cdc1..139cd49b2c27 100644 --- a/io_uring/io-wq.c +++ b/io_uring/io-wq.c @@ -628,7 +628,7 @@ static int io_wqe_worker(void *data) struct io_wqe_acct *acct = io_wqe_get_acct(worker); struct io_wqe *wqe = worker->wqe; struct io_wq *wq = wqe->wq; - bool last_timeout = false; + bool exit_mask = false, last_timeout = false; char buf[TASK_COMM_LEN]; worker->flags |= (IO_WORKER_F_UP | IO_WORKER_F_RUNNING); @@ -644,8 +644,11 @@ static int io_wqe_worker(void *data) io_worker_handle_work(worker); raw_spin_lock(&wqe->lock); - /* timed out, exit unless we're the last worker */ - if (last_timeout && acct->nr_workers > 1) { + /* + * Last sleep timed out. Exit if we're not the last worker, + * or if someone modified our affinity. + */ + if (last_timeout && (exit_mask || acct->nr_workers > 1)) { acct->nr_workers--; raw_spin_unlock(&wqe->lock); __set_current_state(TASK_RUNNING); @@ -664,7 +667,11 @@ static int io_wqe_worker(void *data) continue; break; } - last_timeout = !ret; + if (!ret) { + last_timeout = true; + exit_mask = !cpumask_test_cpu(raw_smp_processor_id(), + wqe->cpu_mask); + } } if (test_bit(IO_WQ_BIT_EXIT, &wq->state)) @@ -716,7 +723,6 @@ static void io_init_new_worker(struct io_wqe *wqe, struct io_worker *worker, tsk->worker_private = worker; worker->task = tsk; set_cpus_allowed_ptr(tsk, wqe->cpu_mask); - tsk->flags |= PF_NO_SETAFFINITY; raw_spin_lock(&wqe->lock); hlist_nulls_add_head_rcu(&worker->nulls_node, &wqe->free_list); -- 2.39.2