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=-7.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 D8D45C2D0EE for ; Tue, 31 Mar 2020 19:29:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A0F0B21556 for ; Tue, 31 Mar 2020 19:29:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="baZCKiyJ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731062AbgCaT24 (ORCPT ); Tue, 31 Mar 2020 15:28:56 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:52950 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1730533AbgCaT21 (ORCPT ); Tue, 31 Mar 2020 15:28:27 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1585682906; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=0GUPuc0LB1+DwbqXNlKtNDBywCBrn0kzY5vXvoKJhT0=; b=baZCKiyJGTOfegPkP9nnj/qM0OAeLD4ITJrjFXrgrv9347aWuA1J/4lYxIJawlPdhS/dyF le1b4QPp7fKaDxqgZXvIyZI9G9tuYGxPy187KBQkuUM0jWbDUD0VeibpPNclXIfGuNSCGs yZvwpffhmQxSHv6GW0zSHN3BEkgJ2G4= 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-365-zdMphn8ePVq7hL0SqzGSUg-1; Tue, 31 Mar 2020 15:28:25 -0400 X-MC-Unique: zdMphn8ePVq7hL0SqzGSUg-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 7726518A6ECF; Tue, 31 Mar 2020 19:28:23 +0000 (UTC) Received: from eperezma.remote.csb (ovpn-112-92.ams2.redhat.com [10.36.112.92]) by smtp.corp.redhat.com (Postfix) with ESMTP id 3368A98A52; Tue, 31 Mar 2020 19:28:21 +0000 (UTC) From: =?UTF-8?q?Eugenio=20P=C3=A9rez?= To: "Michael S. Tsirkin" Cc: "linux-kernel@vger.kernel.org" , Stephen Rothwell , kvm list , Linux Next Mailing List , "virtualization@lists.linux-foundation.org" , =?UTF-8?q?Eugenio=20P=C3=A9rez?= , Christian Borntraeger , Halil Pasic , Cornelia Huck Subject: [PATCH v3 4/8] vhost: batching fetches Date: Tue, 31 Mar 2020 21:28:00 +0200 Message-Id: <20200331192804.6019-5-eperezma@redhat.com> In-Reply-To: <20200331192804.6019-1-eperezma@redhat.com> References: <20200331192804.6019-1-eperezma@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Content-Transfer-Encoding: quoted-printable Sender: linux-next-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-next@vger.kernel.org From: "Michael S. Tsirkin" With this patch applied, new and old code perform identically. Lots of extra optimizations are now possible, e.g. we can fetch multiple heads with copy_from/to_user now. We can get rid of maintaining the log array. Etc etc. Signed-off-by: Michael S. Tsirkin Signed-off-by: Eugenio P=C3=A9rez --- drivers/vhost/test.c | 2 +- drivers/vhost/vhost.c | 47 ++++++++++++++++++++++++++++++++++++++----- drivers/vhost/vhost.h | 5 ++++- 3 files changed, 47 insertions(+), 7 deletions(-) diff --git a/drivers/vhost/test.c b/drivers/vhost/test.c index 394e2e5c772d..4b00cd4266ad 100644 --- a/drivers/vhost/test.c +++ b/drivers/vhost/test.c @@ -119,7 +119,7 @@ static int vhost_test_open(struct inode *inode, struc= t file *f) dev =3D &n->dev; vqs[VHOST_TEST_VQ] =3D &n->vqs[VHOST_TEST_VQ]; n->vqs[VHOST_TEST_VQ].handle_kick =3D handle_vq_kick; - vhost_dev_init(dev, vqs, VHOST_TEST_VQ_MAX, UIO_MAXIOV, + vhost_dev_init(dev, vqs, VHOST_TEST_VQ_MAX, UIO_MAXIOV + 64, VHOST_TEST_PKT_WEIGHT, VHOST_TEST_WEIGHT); =20 f->private_data =3D n; diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 56c5253056ee..1646b1ce312a 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -303,6 +303,7 @@ static void vhost_vq_reset(struct vhost_dev *dev, { vq->num =3D 1; vq->ndescs =3D 0; + vq->first_desc =3D 0; vq->desc =3D NULL; vq->avail =3D NULL; vq->used =3D NULL; @@ -371,6 +372,11 @@ static int vhost_worker(void *data) return 0; } =20 +static int vhost_vq_num_batch_descs(struct vhost_virtqueue *vq) +{ + return vq->max_descs - UIO_MAXIOV; +} + static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq) { kfree(vq->descs); @@ -393,6 +399,9 @@ static long vhost_dev_alloc_iovecs(struct vhost_dev *= dev) for (i =3D 0; i < dev->nvqs; ++i) { vq =3D dev->vqs[i]; vq->max_descs =3D dev->iov_limit; + if (vhost_vq_num_batch_descs(vq) < 0) { + return -EINVAL; + } vq->descs =3D kmalloc_array(vq->max_descs, sizeof(*vq->descs), GFP_KERNEL); @@ -1643,6 +1652,7 @@ long vhost_vring_ioctl(struct vhost_dev *d, unsigne= d int ioctl, void __user *arg vq->last_avail_idx =3D s.num; /* Forget the cached index value. */ vq->avail_idx =3D vq->last_avail_idx; + vq->ndescs =3D vq->first_desc =3D 0; break; case VHOST_GET_VRING_BASE: s.index =3D idx; @@ -2211,7 +2221,7 @@ static int fetch_indirect_descs(struct vhost_virtqu= eue *vq, return 0; } =20 -static int fetch_descs(struct vhost_virtqueue *vq) +static int fetch_buf(struct vhost_virtqueue *vq) { unsigned int i, head, found =3D 0; struct vhost_desc *last; @@ -2224,7 +2234,11 @@ static int fetch_descs(struct vhost_virtqueue *vq) /* Check it isn't doing very strange things with descriptor numbers. */ last_avail_idx =3D vq->last_avail_idx; =20 - if (vq->avail_idx =3D=3D vq->last_avail_idx) { + if (unlikely(vq->avail_idx =3D=3D vq->last_avail_idx)) { + /* If we already have work to do, don't bother re-checking. */ + if (likely(vq->ndescs)) + return vq->num; + if (unlikely(vhost_get_avail_idx(vq, &avail_idx))) { vq_err(vq, "Failed to access avail idx at %p\n", &vq->avail->idx); @@ -2315,6 +2329,24 @@ static int fetch_descs(struct vhost_virtqueue *vq) return 0; } =20 +static int fetch_descs(struct vhost_virtqueue *vq) +{ + int ret =3D 0; + + if (unlikely(vq->first_desc >=3D vq->ndescs)) { + vq->first_desc =3D 0; + vq->ndescs =3D 0; + } + + if (vq->ndescs) + return 0; + + while (!ret && vq->ndescs <=3D vhost_vq_num_batch_descs(vq)) + ret =3D fetch_buf(vq); + + return vq->ndescs ? 0 : ret; +} + /* This looks in the virtqueue and for the first available buffer, and c= onverts * it to an iovec for convenient access. Since descriptors consist of s= ome * number of output then some number of input descriptors, it's actually= two @@ -2340,7 +2372,7 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq, if (unlikely(log)) *log_num =3D 0; =20 - for (i =3D 0; i < vq->ndescs; ++i) { + for (i =3D vq->first_desc; i < vq->ndescs; ++i) { unsigned iov_count =3D *in_num + *out_num; struct vhost_desc *desc =3D &vq->descs[i]; int access; @@ -2386,14 +2418,19 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq, } =20 ret =3D desc->id; + + if (!(desc->flags & VRING_DESC_F_NEXT)) + break; } =20 - vq->ndescs =3D 0; + vq->first_desc =3D i + 1; =20 return ret; =20 err: - vhost_discard_vq_desc(vq, 1); + for (i =3D vq->first_desc; i < vq->ndescs; ++i) + if (!(vq->descs[i].flags & VRING_DESC_F_NEXT)) + vhost_discard_vq_desc(vq, 1); vq->ndescs =3D 0; =20 return ret; diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h index 1dbb5e44fba4..e1caca605c56 100644 --- a/drivers/vhost/vhost.h +++ b/drivers/vhost/vhost.h @@ -100,6 +100,7 @@ struct vhost_virtqueue { =20 struct vhost_desc *descs; int ndescs; + int first_desc; int max_descs; =20 const struct vhost_umem_node *meta_iotlb[VHOST_NUM_ADDRS]; @@ -242,7 +243,7 @@ ssize_t vhost_chr_write_iter(struct vhost_dev *dev, int vhost_init_device_iotlb(struct vhost_dev *d, bool enabled); =20 #define vq_err(vq, fmt, ...) do { \ - pr_debug(pr_fmt(fmt), ##__VA_ARGS__); \ + pr_err(pr_fmt(fmt), ##__VA_ARGS__); \ if ((vq)->error_ctx) \ eventfd_signal((vq)->error_ctx, 1);\ } while (0) @@ -268,6 +269,8 @@ static inline void vhost_vq_set_backend(struct vhost_= virtqueue *vq, void *private_data) { vq->private_data =3D private_data; + vq->ndescs =3D 0; + vq->first_desc =3D 0; } =20 /** --=20 2.18.1