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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EC45EC433EF for ; Mon, 22 Nov 2021 13:20:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238838AbhKVNYE (ORCPT ); Mon, 22 Nov 2021 08:24:04 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:48253 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231444AbhKVNYE (ORCPT ); Mon, 22 Nov 2021 08:24:04 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1637587257; 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=+lF/w7tD9pxUXDtV6yAcEsR2+KOGUo37EC26aybNgIE=; b=RrKMk8v/uAU2aXCEZw/cBJa4XbcEE/8QtLKjwP3K4m5ZZEruOV1I1frtcEEOtP8qCw5oLY 8aNvTXDMSswHoUxkvoumUMW0Fv1fGsgsnQu630ynzr69iCT+qlBinTYFRBp8xBfUXDyl44 gEHKZtYph2MUod8zh6c329NjQ9i2HUo= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-286-Y6l1Z9kiOSyzdEGWU2bqxQ-1; Mon, 22 Nov 2021 08:20:43 -0500 X-MC-Unique: Y6l1Z9kiOSyzdEGWU2bqxQ-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 1D04EA40C6; Mon, 22 Nov 2021 13:20:42 +0000 (UTC) Received: from T590 (ovpn-8-23.pek2.redhat.com [10.72.8.23]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 5A92F5B826; Mon, 22 Nov 2021 13:20:14 +0000 (UTC) Date: Mon, 22 Nov 2021 21:20:10 +0800 From: Ming Lei To: Sagi Grimberg Cc: Christoph Hellwig , Jens Axboe , "Martin K . Petersen" , linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, linux-scsi@vger.kernel.org, Keith Busch Subject: Re: [PATCH 2/5] blk-mq: rename hctx_lock & hctx_unlock Message-ID: References: <20211119021849.2259254-1-ming.lei@redhat.com> <20211119021849.2259254-3-ming.lei@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org On Mon, Nov 22, 2021 at 09:53:53AM +0200, Sagi Grimberg wrote: > > > -static inline void hctx_unlock(struct blk_mq_hw_ctx *hctx, int srcu_idx) > > - __releases(hctx->srcu) > > +static inline void queue_unlock(struct request_queue *q, bool blocking, > > + int srcu_idx) > > + __releases(q->srcu) > > { > > - if (!(hctx->flags & BLK_MQ_F_BLOCKING)) > > + if (!blocking) > > rcu_read_unlock(); > > else > > - srcu_read_unlock(hctx->queue->srcu, srcu_idx); > > + srcu_read_unlock(q->srcu, srcu_idx); > > Maybe instead of passing blocking bool just look at srcu_idx? > > if (srcu_idx < 0) > rcu_read_unlock(); > else > srcu_read_unlock(q->srcu, srcu_idx); This way needs to initialize srcu_idx in each callers. > > Or look if the queue has srcu allocated? > > if (!q->srcu) > rcu_read_unlock(); > else > srcu_read_unlock(q->srcu, srcu_idx); This way is worse since q->srcu may involve one new cacheline fetch. hctx->flags is always hot, so it is basically zero cost to check it. Thanks, Ming