From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C5347C433C1 for ; Thu, 25 Mar 2021 00:33:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 75F8A61A14 for ; Thu, 25 Mar 2021 00:33:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239327AbhCYAc2 (ORCPT ); Wed, 24 Mar 2021 20:32:28 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:31853 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239326AbhCYAcQ (ORCPT ); Wed, 24 Mar 2021 20:32:16 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1616632335; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Q3e27mFe+SdlrRkFTD0Oi5wfD4h0zwYD1ZYIdliuSD4=; b=aqhD5Bi8q+hUzkZ54/IIMgz6uQxhaU9s9BFLWORPfTj9Pz1KxD859KtTbNt+CmZPQ3B+kR GZoS/drsYhHGM0pqubmOstUVQ4Ax2bidHuI5MASqyNyy0RvP2U83mzYzwGextU9w/Bk4Yo v0kv+sVykgD/vHgWXqmICQzaCsA7ZbE= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-394-wOVQGhhfM5i1cd-HZK_ljA-1; Wed, 24 Mar 2021 20:32:14 -0400 X-MC-Unique: wOVQGhhfM5i1cd-HZK_ljA-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id CD2501B2C981; Thu, 25 Mar 2021 00:32:12 +0000 (UTC) Received: from T590 (ovpn-12-137.pek2.redhat.com [10.72.12.137]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B18355D723; Thu, 25 Mar 2021 00:32:07 +0000 (UTC) Date: Thu, 25 Mar 2021 08:32:02 +0800 From: Ming Lei To: Hannes Reinecke Cc: Jens Axboe , linux-block@vger.kernel.org, Jeffle Xu , Mike Snitzer , dm-devel@redhat.com Subject: Re: [PATCH V3 05/13] block: add req flag of REQ_POLL_CTX Message-ID: References: <20210324121927.362525-1-ming.lei@redhat.com> <20210324121927.362525-6-ming.lei@redhat.com> <614dcf6d-2b45-394c-d295-c14c14dc9070@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <614dcf6d-2b45-394c-d295-c14c14dc9070@suse.de> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Wed, Mar 24, 2021 at 04:32:31PM +0100, Hannes Reinecke wrote: > On 3/24/21 1:19 PM, Ming Lei wrote: > > Add one req flag REQ_POLL_CTX which will be used in the following patch for > > supporting bio based IO polling. > > > > Exactly this flag can help us to do: > > > > 1) request flag is cloned in bio_fast_clone(), so if we mark one FS bio > > as REQ_POLL_CTX, all bios cloned from this FS bio will be marked as > > REQ_POLL_CTX too. > > > > 2) create per-task io polling context if the bio based queue supports > > polling and the submitted bio is HIPRI. Per-task io poll context will be > > created during submit_bio() before marking this HIPRI bio as REQ_POLL_CTX. > > Then we can avoid to create such io polling context if one cloned bio with > > REQ_POLL_CTX is submitted from another kernel context. > > > > 3) for supporting bio based io polling, we need to poll IOs from all > > underlying queues of the bio device, this way help us to recognize which > > IO needs to polled in bio based style, which will be applied in > > following patch. > > > > Signed-off-by: Ming Lei > > --- > > block/blk-core.c | 25 ++++++++++++++++++++++++- > > include/linux/blk_types.h | 4 ++++ > > 2 files changed, 28 insertions(+), 1 deletion(-) > > > > diff --git a/block/blk-core.c b/block/blk-core.c > > index 4671bbf31fd3..eb07d61cfdc2 100644 > > --- a/block/blk-core.c > > +++ b/block/blk-core.c > > @@ -840,11 +840,30 @@ static inline bool blk_queue_support_bio_poll(struct request_queue *q) > > static inline void blk_bio_poll_preprocess(struct request_queue *q, > > struct bio *bio) > > { > > + bool mq; > > + > > if (!(bio->bi_opf & REQ_HIPRI)) > > return; > > - if (!blk_queue_poll(q) || (!queue_is_mq(q) && !blk_get_bio_poll_ctx())) > > + /* > > + * Can't support bio based IO polling without per-task poll ctx > > + * > > + * We have created per-task io poll context, and mark this > > + * bio as REQ_POLL_CTX, so: 1) if any cloned bio from this bio is > > + * submitted from another kernel context, we won't create bio > > + * poll context for it, and that bio can be completed by IRQ; > > + * 2) If such bio is submitted from current context, we will > > + * complete it via blk_poll(); 3) If driver knows that one > > + * underlying bio allocated from driver is for FS bio, meantime > > + * it is submitted in current context, driver can mark such bio > > + * as REQ_HIPRI & REQ_POLL_CTX manually, so the bio can be completed > > + * via blk_poll too. > > + */ > > + mq = queue_is_mq(q); > > + if (!blk_queue_poll(q) || (!mq && !blk_get_bio_poll_ctx())) > > bio->bi_opf &= ~REQ_HIPRI; > > + else if (!mq) > > + bio->bi_opf |= REQ_POLL_CTX; > > } > > static noinline_for_stack bool submit_bio_checks(struct bio *bio) > > @@ -894,8 +913,12 @@ static noinline_for_stack bool submit_bio_checks(struct bio *bio) > > /* > > * Create per-task io poll ctx if bio polling supported and HIPRI > > * set. > > + * > > + * If REQ_POLL_CTX isn't set for this HIPRI bio, we think it originated > > + * from FS and allocate io polling context. > > */ > > blk_create_io_context(q, blk_queue_support_bio_poll(q) && > > + !(bio->bi_opf & REQ_POLL_CTX) && > > (bio->bi_opf & REQ_HIPRI)); > > blk_bio_poll_preprocess(q, bio); > > diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h > > index db026b6ec15a..99160d588c2d 100644 > > --- a/include/linux/blk_types.h > > +++ b/include/linux/blk_types.h > > @@ -394,6 +394,9 @@ enum req_flag_bits { > > __REQ_HIPRI, > > + /* for marking IOs originated from same FS bio in same context */ > > + __REQ_POLL_CTX, > > + > > /* for driver use */ > > __REQ_DRV, > > __REQ_SWAP, /* swapping request. */ > > @@ -418,6 +421,7 @@ enum req_flag_bits { > > #define REQ_NOUNMAP (1ULL << __REQ_NOUNMAP) > > #define REQ_HIPRI (1ULL << __REQ_HIPRI) > > +#define REQ_POLL_CTX (1ULL << __REQ_POLL_CTX) > > #define REQ_DRV (1ULL << __REQ_DRV) > > #define REQ_SWAP (1ULL << __REQ_SWAP) > > > What happens to split bios? > Will they be tracked similarly to cloned bios? > If so, shouldn't you document that here, too? split bios are simply cloned bios, please see bio_split(). thanks, Ming