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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 733EBC43461 for ; Thu, 17 Sep 2020 14:58:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 27CC421582 for ; Thu, 17 Sep 2020 14:58:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="GgmJhYxu" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727850AbgIQO6s (ORCPT ); Thu, 17 Sep 2020 10:58:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33570 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727570AbgIQOtD (ORCPT ); Thu, 17 Sep 2020 10:49:03 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1F73AC061351; Thu, 17 Sep 2020 07:47:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=e46ZxCmYJpeJz6E3Pq9hIabq8Ncj/V4WuCKu6cUX04k=; b=GgmJhYxu8pKJ+ZfpFhuO/KjJyt FmOkSlVuFX6W5Ke0+UtWhFqTTiIXtAiUEvVAWpz2n9qUDej5ce/P1keOJeOGFxleNC9illwlgVVZZ Tziy+vgLb9Ad+ITL5FA+fQXPPHX/PLCT6k9Z+wY4iDW4aWNHH5zEptwGHkknAhpkHD/oRBQMbGNhN 4UyBy6tUH1GvypyIWQdwGc2d0d8n0ZmbDOcwv3Qo2JWgFmCwEVxT9QQd/Tu1VMYK2ZQfIT6Iqcr09 3o7Y7VVEN4q74E53lqMa0sVs7MEkyCl55hYnMBUzdM9A1Ci7Dvfr6wtUkqGIyNhHcrylB/hwjDgY+ YUnPjkew==; Received: from hch by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kIvBQ-00088r-K0; Thu, 17 Sep 2020 14:46:48 +0000 Date: Thu, 17 Sep 2020 15:46:48 +0100 From: Christoph Hellwig To: Boaz Harrosh Cc: Matthew Wilcox , Oleg Nesterov , Hou Tao , peterz@infradead.org, Ingo Molnar , Will Deacon , Dennis Zhou , Tejun Heo , Christoph Lameter , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Jan Kara Subject: Re: [RFC PATCH] locking/percpu-rwsem: use this_cpu_{inc|dec}() for read_count Message-ID: <20200917144648.GA31086@infradead.org> References: <20200915140750.137881-1-houtao1@huawei.com> <20200915150610.GC2674@hirez.programming.kicks-ass.net> <20200915153113.GA6881@redhat.com> <20200915155150.GD2674@hirez.programming.kicks-ass.net> <20200915160344.GH35926@hirez.programming.kicks-ass.net> <20200917120132.GA5602@redhat.com> <20200917124838.GT5449@casper.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 17, 2020 at 04:46:38PM +0300, Boaz Harrosh wrote: > From my totally subjective experience on the filesystem side (user of > bio_endio) all HW block drivers I used including Nvme isci, sata... etc. end > up calling bio_endio in softirq. The big exception to that is the vdX > drivers under KVM. Which is very Ironic to me. NVMe normally calls it from hardirq or IPI context. The only time it would use softirq context is if you have a single I/O queue, which is very unusual.