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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 82FF2C54E5D for ; Mon, 18 Mar 2024 18:37:47 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rmHrW-0007Av-GW; Mon, 18 Mar 2024 14:37:30 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rmHrU-0007An-S4 for qemu-devel@nongnu.org; Mon, 18 Mar 2024 14:37:28 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rmHrS-0006TQ-VG for qemu-devel@nongnu.org; Mon, 18 Mar 2024 14:37:28 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1710787046; 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=gJCw9Ax6NFFsTYbQH2IWyNy96ikx9vWcqbj/l0FoQ/I=; b=RhHcFmq9lvAJWq0EygxCEgaS5csNTmFr37ryjXEVZTsFYuhoF8eUgKu3oXQUvgHejCDiW1 od7xT0ItiFMb47X53Wc96HuranjN5nJ/qKCfoxEdcaN2dKF0me/xCyZaePloaHFWCmfI1N 17CqJwSOfX0VpHnSXffgKR1U3UbI7EY= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-78-tmvYnaQnOF6UhQShVgGUkQ-1; Mon, 18 Mar 2024 14:37:22 -0400 X-MC-Unique: tmvYnaQnOF6UhQShVgGUkQ-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 5CFE3282D3C6; Mon, 18 Mar 2024 18:37:22 +0000 (UTC) Received: from localhost (unknown [10.39.194.74]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9D885C017A2; Mon, 18 Mar 2024 18:37:21 +0000 (UTC) Date: Mon, 18 Mar 2024 14:37:16 -0400 From: Stefan Hajnoczi To: qemu-devel@nongnu.org Cc: qemu-block@nongnu.org, "Michael S. Tsirkin" , Kevin Wolf , Hanna Reitz , Sanjay Rao , Boaz Ben Shabat , Joe Mario Subject: Re: [PATCH v2] virtio-blk: iothread-vq-mapping coroutine pool sizing Message-ID: <20240318183716.GA1039373@fedora> References: <20240312151204.412624-1-stefanha@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="aHDpA35URscttHWT" Content-Disposition: inline In-Reply-To: <20240312151204.412624-1-stefanha@redhat.com> X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.8 Received-SPF: pass client-ip=170.10.133.124; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -24 X-Spam_score: -2.5 X-Spam_bar: -- X-Spam_report: (-2.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.374, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org --aHDpA35URscttHWT Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Mar 12, 2024 at 11:12:04AM -0400, Stefan Hajnoczi wrote: > It is possible to hit the sysctl vm.max_map_count limit when the > coroutine pool size becomes large. Each coroutine requires two mappings > (one for the stack and one for the guard page). QEMU can crash with > "failed to set up stack guard page" or "failed to allocate memory for > stack" when this happens. >=20 > Coroutine pool sizing is simple when there is only thread: sum up all > I/O requests across all virtqueues. >=20 > When the iothread-vq-mapping option is used we should calculate tighter > bounds because thread may serve a subset of the device's virtqueues: > take the maximum number of the number of I/O requests across all > virtqueues. A thread does not need coroutine pool space for I/O requests > that are handled by other threads. >=20 > This is not a solution to hitting vm.max_map_count, but it helps. A > guest with 64 vCPUs (hence 64 virtqueues) across 4 IOThreads with one > iothread-vq-mapping virtio-blk device and a root disk without goes from > pool_max_size 16,448 to 10,304. >=20 > Reported-by: Sanjay Rao > Reported-by: Boaz Ben Shabat > Reported-by: Joe Mario > Signed-off-by: Stefan Hajnoczi > --- > v2: > - State the the tighter bounds reflect the fact that threads may only > process a subset of the total I/O requests from a device [Kevin] > - Add Reported-by: Joe Mario, he has been investigating this issue. I have sent a new patch series that obsoletes this patch. Please do not apply this patch. The new series is here: https://lore.kernel.org/qemu-devel/20240318183429.1039340-1-stefanha@redhat= =2Ecom/T/#u >=20 > include/hw/virtio/virtio-blk.h | 2 ++ > hw/block/virtio-blk.c | 34 ++++++++++++++++++++++++++++++++-- > 2 files changed, 34 insertions(+), 2 deletions(-) >=20 > diff --git a/include/hw/virtio/virtio-blk.h b/include/hw/virtio/virtio-bl= k.h > index 5c14110c4b..ac29700ad4 100644 > --- a/include/hw/virtio/virtio-blk.h > +++ b/include/hw/virtio/virtio-blk.h > @@ -74,6 +74,8 @@ struct VirtIOBlock { > uint64_t host_features; > size_t config_size; > BlockRAMRegistrar blk_ram_registrar; > + > + unsigned coroutine_pool_size; > }; > =20 > typedef struct VirtIOBlockReq { > diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c > index 738cb2ac36..0a14b2b175 100644 > --- a/hw/block/virtio-blk.c > +++ b/hw/block/virtio-blk.c > @@ -1957,6 +1957,35 @@ static void virtio_blk_stop_ioeventfd(VirtIODevice= *vdev) > s->ioeventfd_stopping =3D false; > } > =20 > +/* Increase the coroutine pool size to include our I/O requests */ > +static void virtio_blk_inc_coroutine_pool_size(VirtIOBlock *s) > +{ > + VirtIOBlkConf *conf =3D &s->conf; > + unsigned max_requests =3D 0; > + > + /* Tracks the total number of requests for AioContext */ > + g_autoptr(GHashTable) counters =3D g_hash_table_new(NULL, NULL); > + > + /* Call this function after setting up vq_aio_context[] */ > + assert(s->vq_aio_context); > + > + for (unsigned i =3D 0; i < conf->num_queues; i++) { > + AioContext *ctx =3D s->vq_aio_context[i]; > + unsigned n =3D GPOINTER_TO_UINT(g_hash_table_lookup(counters, ct= x)); > + > + n +=3D conf->queue_size / 2; /* this is a heuristic */ > + > + g_hash_table_insert(counters, ctx, GUINT_TO_POINTER(n)); > + > + if (n > max_requests) { > + max_requests =3D n; > + } > + } > + > + qemu_coroutine_inc_pool_size(max_requests); > + s->coroutine_pool_size =3D max_requests; /* stash it for ->unrealize= () */ > +} > + > static void virtio_blk_device_realize(DeviceState *dev, Error **errp) > { > VirtIODevice *vdev =3D VIRTIO_DEVICE(dev); > @@ -2048,7 +2077,6 @@ static void virtio_blk_device_realize(DeviceState *= dev, Error **errp) > for (i =3D 0; i < conf->num_queues; i++) { > virtio_add_queue(vdev, conf->queue_size, virtio_blk_handle_outpu= t); > } > - qemu_coroutine_inc_pool_size(conf->num_queues * conf->queue_size / 2= ); > =20 > /* Don't start ioeventfd if transport does not support notifiers. */ > if (!virtio_device_ioeventfd_enabled(vdev)) { > @@ -2065,6 +2093,8 @@ static void virtio_blk_device_realize(DeviceState *= dev, Error **errp) > return; > } > =20 > + virtio_blk_inc_coroutine_pool_size(s); > + > /* > * This must be after virtio_init() so virtio_blk_dma_restart_cb() g= ets > * called after ->start_ioeventfd() has already set blk's AioContext. > @@ -2096,7 +2126,7 @@ static void virtio_blk_device_unrealize(DeviceState= *dev) > for (i =3D 0; i < conf->num_queues; i++) { > virtio_del_queue(vdev, i); > } > - qemu_coroutine_dec_pool_size(conf->num_queues * conf->queue_size / 2= ); > + qemu_coroutine_dec_pool_size(s->coroutine_pool_size); > qemu_mutex_destroy(&s->rq_lock); > blk_ram_registrar_destroy(&s->blk_ram_registrar); > qemu_del_vm_change_state_handler(s->change); > --=20 > 2.44.0 >=20 --aHDpA35URscttHWT Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEhpWov9P5fNqsNXdanKSrs4Grc8gFAmX4idsACgkQnKSrs4Gr c8hsLAgAq+XcGrALp8SatUKQnYsRtOkzpcHUxcAM3bTYpEzhUli2501sP/EiLgdI DDtlO+Pn7oUNid6oHj1snmwNllzw7tZf38hOJrgKKwTZIjSuKkchNZ/Hgl8xnMVQ KSlYnWcxtepR4SlSNihPvPu+Tydv3+M70JAchBEpy5xHfcJma307q5hFn7XydTlp xc21PgQLuQeufAs0ggM2b7KXFSVampZ9c6SsANsPtN/jsY/wcpE534PCt7CzUbfn bNNtR6vo9ZP0eAUhn/WQsow+3H5aJgGBoKSePxsrhz56KpvQ6K7QTeiHIgKm6Lko ue08THrm5KXcihIidL7Gzeez0oAUkw== =Tf6n -----END PGP SIGNATURE----- --aHDpA35URscttHWT--