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=-4.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 54E11C433E3 for ; Tue, 28 Jul 2020 09:33:53 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 226AA20714 for ; Tue, 28 Jul 2020 09:33:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="ZZu7AfPX"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="NYig39eU" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 226AA20714 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=E5vrjJIh9gccWoDf5Em+XuK156pqvgvir6BvKALwdcc=; b=ZZu7AfPXnNINk37yXOwgHlcZG rguyxtp2Tnw0+zMA+655dTdPnpH5qGp9MPgUQ22Ce/9kA/TEikNIxWjLAqpDIZAslaqRD+Ltwj11z ZIVYqxkLJ1WpyJvH37ZOsBSFegJRnaskC5pA9IhYSXHd5tHUS1lu6SDcOb9b+4mRvMUaDyVvXusB0 CswGcukSgsRUY8msN1PPmCvqDiQf5Cae/a0wB/3lv10gQR/avtPbW2mnbk8GRgnBMuMRxJbrhLnXV GgeZT9ppnSv8Et4YVBjSXThfGhQcKcf4dsc+UUxDMuLlbopaMMOT1hdN+hsYs6qV66cyrwtDkGcLS X32+COBRg==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1k0LzZ-000102-Ep; Tue, 28 Jul 2020 09:33:49 +0000 Received: from us-smtp-1.mimecast.com ([207.211.31.81] helo=us-smtp-delivery-1.mimecast.com) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1k0LzX-0000zY-62 for linux-nvme@lists.infradead.org; Tue, 28 Jul 2020 09:33:47 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1595928826; 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=dGU4qL4DU0btEF4z3eSCu70P6IJAwTZBKSCRVuLZFTQ=; b=NYig39eUF3gIfF6AeRbo7t9nG5Rj3wzy1/kw+yeTAYWyAndrXzJUAkhvpXOb566odUHne1 dry3gdM1siWojRReO0RtgtgGH5E8zhudHA3IUP5CCjn4YCOfS+xbchcBKcnShOZbdpBe+E WCOi2KTppVg99w1SAciShYVSZbMtLII= 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-41-WHshVYmMO3SvupRBQkriyA-1; Tue, 28 Jul 2020 05:33:42 -0400 X-MC-Unique: WHshVYmMO3SvupRBQkriyA-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 4E5EB800597; Tue, 28 Jul 2020 09:33:40 +0000 (UTC) Received: from T590 (ovpn-12-109.pek2.redhat.com [10.72.12.109]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7EB1190E63; Tue, 28 Jul 2020 09:33:31 +0000 (UTC) Date: Tue, 28 Jul 2020 17:33:26 +0800 From: Ming Lei To: Sagi Grimberg Subject: Re: [PATCH v5 1/2] blk-mq: add tagset quiesce interface Message-ID: <20200728093326.GC1326626@T590> References: <20200727231022.307602-1-sagi@grimberg.me> <20200727231022.307602-2-sagi@grimberg.me> <20200728071859.GA21629@lst.de> <20200728091633.GB1326626@T590> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200728_053347_258981_D6172ED7 X-CRM114-Status: GOOD ( 23.30 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jens Axboe , "Paul E. McKenney" , linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, Chao Leng , Keith Busch , Ming Lin , Christoph Hellwig Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Tue, Jul 28, 2020 at 02:24:38AM -0700, Sagi Grimberg wrote: > > > > I like the tagset based interface. But the idea of doing a per-hctx > > > allocation and wait doesn't seem very scalable. > > > > > > Paul, do you have any good idea for an interface that waits on > > > multiple srcu heads? As far as I can tell we could just have a single > > > global completion and counter, and each call_srcu would just just > > > decrement it and then the final one would do the wakeup. It would just > > > be great to figure out a way to keep the struct rcu_synchronize and > > > counter on stack to avoid an allocation. > > > > > > But if we can't do with an on-stack object I'd much rather just embedd > > > the rcu_head in the hw_ctx. > > > > I think we can do that, please see the following patch which is against Sagi's V5: > > I don't think you can send a single rcu_head to multiple call_srcu calls. OK, then one variant is to put the rcu_head into blk_mq_hw_ctx, and put rcu_synchronize into blk_mq_tag_set. Thanks, Ming _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme