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=-7.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham 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 9FAF4C4740A for ; Mon, 9 Sep 2019 16:10:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 802222082C for ; Mon, 9 Sep 2019 16:10:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728887AbfIIQK5 (ORCPT ); Mon, 9 Sep 2019 12:10:57 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49674 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726784AbfIIQK4 (ORCPT ); Mon, 9 Sep 2019 12:10:56 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 2841C31752A7; Mon, 9 Sep 2019 16:10:56 +0000 (UTC) Received: from localhost (ovpn-117-107.ams2.redhat.com [10.36.117.107]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1F76C60BF4; Mon, 9 Sep 2019 16:10:50 +0000 (UTC) Date: Mon, 9 Sep 2019 18:10:45 +0200 From: Stefan Hajnoczi To: "Michael S. Tsirkin" Cc: Vivek Goyal , linux-fsdevel@vger.kernel.org, virtualization@lists.linux-foundation.org, miklos@szeredi.hu, linux-kernel@vger.kernel.org, virtio-fs@redhat.com, dgilbert@redhat.com Subject: Re: [PATCH 08/18] virtiofs: Drain all pending requests during ->remove time Message-ID: <20190909161045.GD20875@stefanha-x1.localdomain> References: <20190905194859.16219-1-vgoyal@redhat.com> <20190905194859.16219-9-vgoyal@redhat.com> <20190906105210.GP5900@stefanha-x1.localdomain> <20190906141705.GF22083@redhat.com> <20190906101819-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="d01dLTUuW90fS44H" Content-Disposition: inline In-Reply-To: <20190906101819-mutt-send-email-mst@kernel.org> User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.49]); Mon, 09 Sep 2019 16:10:56 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --d01dLTUuW90fS44H Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Sep 06, 2019 at 10:18:49AM -0400, Michael S. Tsirkin wrote: > On Fri, Sep 06, 2019 at 10:17:05AM -0400, Vivek Goyal wrote: > > On Fri, Sep 06, 2019 at 11:52:10AM +0100, Stefan Hajnoczi wrote: > > > On Thu, Sep 05, 2019 at 03:48:49PM -0400, Vivek Goyal wrote: > > > > +static void virtio_fs_drain_queue(struct virtio_fs_vq *fsvq) > > > > +{ > > > > + WARN_ON(fsvq->in_flight < 0); > > > > + > > > > + /* Wait for in flight requests to finish.*/ > > > > + while (1) { > > > > + spin_lock(&fsvq->lock); > > > > + if (!fsvq->in_flight) { > > > > + spin_unlock(&fsvq->lock); > > > > + break; > > > > + } > > > > + spin_unlock(&fsvq->lock); > > > > + usleep_range(1000, 2000); > > > > + } > > >=20 > > > I think all contexts that call this allow sleeping so we could avoid > > > usleep here. > >=20 > > usleep_range() is supposed to be used from non-atomic context. > >=20 > > https://github.com/torvalds/linux/blob/master/Documentation/timers/time= rs-howto.rst > >=20 > > What construct you are thinking of? > >=20 > > Vivek >=20 > completion + signal on vq callback? Yes. Time-based sleep() is sub-optimal because we could wake up exactly when in_flight is decremented from the vq callback. This avoids unnecessary sleep wakeups and the extra time spent sleeping after in_flight has been decremented. Stefan --d01dLTUuW90fS44H Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEhpWov9P5fNqsNXdanKSrs4Grc8gFAl12eYUACgkQnKSrs4Gr c8gSKQgAnEAvX9YIhk4yOMGl/UMlOnxBybw15xYg29qYtIPTCBl5Px/k0kPkDeK/ iHnhS/2epJz36c5DV0GEfGGX1HCzcKt9zLHZ5RI7NKV5HV5pBKsftliW6gY0yo/p z0+lghQwP7izbE1EpPGWHichCu+hctoBnwlckg6TFmJxs+xWeSwdsDJ8Vya28tQl IXvedRgLh0fOX8F7ZkH0pRrmAkzcERWoXjf17QeOEsntwzWWZ9/1LYOwzMo/1imn exUSUMA7NFgVr4esi8G1LM3kHJRoaQcwCmSN9GGAc2dpUblNzwW04kmD6wAMpOXA DvrZS9U0BxnNqVjpKlNjyH7fRY7epA== =8+oH -----END PGP SIGNATURE----- --d01dLTUuW90fS44H-- From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 9 Sep 2019 18:10:45 +0200 From: Stefan Hajnoczi Message-ID: <20190909161045.GD20875@stefanha-x1.localdomain> References: <20190905194859.16219-1-vgoyal@redhat.com> <20190905194859.16219-9-vgoyal@redhat.com> <20190906105210.GP5900@stefanha-x1.localdomain> <20190906141705.GF22083@redhat.com> <20190906101819-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="d01dLTUuW90fS44H" Content-Disposition: inline In-Reply-To: <20190906101819-mutt-send-email-mst@kernel.org> Subject: Re: [Virtio-fs] [PATCH 08/18] virtiofs: Drain all pending requests during ->remove time List-Id: Development discussions about virtio-fs List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: miklos@szeredi.hu, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, virtio-fs@redhat.com, linux-fsdevel@vger.kernel.org, Vivek Goyal --d01dLTUuW90fS44H Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Sep 06, 2019 at 10:18:49AM -0400, Michael S. Tsirkin wrote: > On Fri, Sep 06, 2019 at 10:17:05AM -0400, Vivek Goyal wrote: > > On Fri, Sep 06, 2019 at 11:52:10AM +0100, Stefan Hajnoczi wrote: > > > On Thu, Sep 05, 2019 at 03:48:49PM -0400, Vivek Goyal wrote: > > > > +static void virtio_fs_drain_queue(struct virtio_fs_vq *fsvq) > > > > +{ > > > > + WARN_ON(fsvq->in_flight < 0); > > > > + > > > > + /* Wait for in flight requests to finish.*/ > > > > + while (1) { > > > > + spin_lock(&fsvq->lock); > > > > + if (!fsvq->in_flight) { > > > > + spin_unlock(&fsvq->lock); > > > > + break; > > > > + } > > > > + spin_unlock(&fsvq->lock); > > > > + usleep_range(1000, 2000); > > > > + } > > >=20 > > > I think all contexts that call this allow sleeping so we could avoid > > > usleep here. > >=20 > > usleep_range() is supposed to be used from non-atomic context. > >=20 > > https://github.com/torvalds/linux/blob/master/Documentation/timers/time= rs-howto.rst > >=20 > > What construct you are thinking of? > >=20 > > Vivek >=20 > completion + signal on vq callback? Yes. Time-based sleep() is sub-optimal because we could wake up exactly when in_flight is decremented from the vq callback. This avoids unnecessary sleep wakeups and the extra time spent sleeping after in_flight has been decremented. Stefan --d01dLTUuW90fS44H Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEhpWov9P5fNqsNXdanKSrs4Grc8gFAl12eYUACgkQnKSrs4Gr c8gSKQgAnEAvX9YIhk4yOMGl/UMlOnxBybw15xYg29qYtIPTCBl5Px/k0kPkDeK/ iHnhS/2epJz36c5DV0GEfGGX1HCzcKt9zLHZ5RI7NKV5HV5pBKsftliW6gY0yo/p z0+lghQwP7izbE1EpPGWHichCu+hctoBnwlckg6TFmJxs+xWeSwdsDJ8Vya28tQl IXvedRgLh0fOX8F7ZkH0pRrmAkzcERWoXjf17QeOEsntwzWWZ9/1LYOwzMo/1imn exUSUMA7NFgVr4esi8G1LM3kHJRoaQcwCmSN9GGAc2dpUblNzwW04kmD6wAMpOXA DvrZS9U0BxnNqVjpKlNjyH7fRY7epA== =8+oH -----END PGP SIGNATURE----- --d01dLTUuW90fS44H--