From: Jason Wang <jasowang@redhat.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: linux-kernel@vger.kernel.org,
"Eugenio Pérez" <eperezma@redhat.com>,
kvm@vger.kernel.org, virtualization@lists.linux-foundation.org,
netdev@vger.kernel.org
Subject: Re: [PATCH RFC 03/13] vhost: batching fetches
Date: Fri, 5 Jun 2020 11:40:17 +0800 [thread overview]
Message-ID: <6c2e6cc7-27c5-445b-f252-0356ff8a83f3@redhat.com> (raw)
In-Reply-To: <20200604045830-mutt-send-email-mst@kernel.org>
On 2020/6/4 下午4:59, Michael S. Tsirkin wrote:
> On Wed, Jun 03, 2020 at 03:27:39PM +0800, Jason Wang wrote:
>> On 2020/6/2 下午9:06, Michael S. Tsirkin wrote:
>>> 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<mst@redhat.com>
>>> Signed-off-by: Eugenio Pérez<eperezma@redhat.com>
>>> Link:https://lore.kernel.org/r/20200401183118.8334-4-eperezma@redhat.com
>>> Signed-off-by: Michael S. Tsirkin<mst@redhat.com>
>>> ---
>>> 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 9a3a09005e03..02806d6f84ef 100644
>>> --- a/drivers/vhost/test.c
>>> +++ b/drivers/vhost/test.c
>>> @@ -119,7 +119,7 @@ static int vhost_test_open(struct inode *inode, struct file *f)
>>> dev = &n->dev;
>>> vqs[VHOST_TEST_VQ] = &n->vqs[VHOST_TEST_VQ];
>>> n->vqs[VHOST_TEST_VQ].handle_kick = 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, NULL);
>>> f->private_data = n;
>>> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
>>> index 8f9a07282625..aca2a5b0d078 100644
>>> --- a/drivers/vhost/vhost.c
>>> +++ b/drivers/vhost/vhost.c
>>> @@ -299,6 +299,7 @@ static void vhost_vq_reset(struct vhost_dev *dev,
>>> {
>>> vq->num = 1;
>>> vq->ndescs = 0;
>>> + vq->first_desc = 0;
>>> vq->desc = NULL;
>>> vq->avail = NULL;
>>> vq->used = NULL;
>>> @@ -367,6 +368,11 @@ static int vhost_worker(void *data)
>>> return 0;
>>> }
>>> +static int vhost_vq_num_batch_descs(struct vhost_virtqueue *vq)
>>> +{
>>> + return vq->max_descs - UIO_MAXIOV;
>>> +}
>> 1 descriptor does not mean 1 iov, e.g userspace may pass several 1 byte
>> length memory regions for us to translate.
>>
> Yes but I don't see the relevance. This tells us how many descriptors to
> batch, not how many IOVs.
Yes, but questions are:
- this introduce another obstacle to support more than 1K queue size
- if we support 1K queue size, does it mean we need to cache 1K
descriptors, which seems a large stress on the cache
Thanks
>
next prev parent reply other threads:[~2020-06-05 3:40 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-02 13:05 [PATCH RFC 00/13] vhost: format independence Michael S. Tsirkin
2020-06-02 13:05 ` [PATCH RFC 01/13] vhost: option to fetch descriptors through an independent struct Michael S. Tsirkin
2020-06-03 7:13 ` Jason Wang
2020-06-03 9:48 ` Michael S. Tsirkin
2020-06-03 12:04 ` Jason Wang
2020-06-07 13:59 ` Michael S. Tsirkin
2020-06-02 13:05 ` [PATCH RFC 02/13] vhost: use batched version by default Michael S. Tsirkin
2020-06-03 7:15 ` Jason Wang
2020-06-02 13:06 ` [PATCH RFC 03/13] vhost: batching fetches Michael S. Tsirkin
2020-06-03 7:27 ` Jason Wang
2020-06-04 8:59 ` Michael S. Tsirkin
2020-06-05 3:40 ` Jason Wang [this message]
2020-06-07 13:57 ` Michael S. Tsirkin
2020-06-08 3:35 ` Jason Wang
2020-06-08 6:01 ` Michael S. Tsirkin
2020-06-02 13:06 ` [PATCH RFC 04/13] vhost: cleanup fetch_buf return code handling Michael S. Tsirkin
2020-06-03 7:29 ` Jason Wang
2020-06-04 9:01 ` Michael S. Tsirkin
2020-06-02 13:06 ` [PATCH RFC 05/13] vhost/net: pass net specific struct pointer Michael S. Tsirkin
2020-06-02 13:06 ` [PATCH RFC 06/13] vhost: reorder functions Michael S. Tsirkin
2020-06-02 13:06 ` [PATCH RFC 07/13] vhost: format-independent API for used buffers Michael S. Tsirkin
2020-06-03 7:58 ` Jason Wang
2020-06-04 9:03 ` Michael S. Tsirkin
2020-06-04 9:18 ` Jason Wang
2020-06-04 10:17 ` Michael S. Tsirkin
2020-06-02 13:06 ` [PATCH RFC 08/13] vhost/net: convert to new API: heads->bufs Michael S. Tsirkin
2020-06-03 8:11 ` Jason Wang
2020-06-04 9:05 ` Michael S. Tsirkin
2020-06-02 13:06 ` [PATCH RFC 09/13] vhost/net: avoid iov length math Michael S. Tsirkin
2020-06-02 13:06 ` [PATCH RFC 10/13] vhost/test: convert to the buf API Michael S. Tsirkin
2020-06-02 13:06 ` [PATCH RFC 11/13] vhost/scsi: switch to buf APIs Michael S. Tsirkin
2020-06-05 8:36 ` Stefan Hajnoczi
2020-06-02 13:06 ` [PATCH RFC 12/13] vhost/vsock: switch to the buf API Michael S. Tsirkin
2020-06-05 8:36 ` Stefan Hajnoczi
2020-06-02 13:06 ` [PATCH RFC 13/13] vhost: drop head based APIs Michael S. Tsirkin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=6c2e6cc7-27c5-445b-f252-0356ff8a83f3@redhat.com \
--to=jasowang@redhat.com \
--cc=eperezma@redhat.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mst@redhat.com \
--cc=netdev@vger.kernel.org \
--cc=virtualization@lists.linux-foundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).