From: Christian Schoenebeck <linux_oss@crudebyte•com>
To: v9fs-developer@lists•sourceforge.net
Cc: netdev@vger•kernel.org,
Dominique Martinet <asmadeus@codewreck•org>,
Eric Van Hensbergen <ericvh@gmail•com>,
Latchesar Ionkov <lucho@ionkov•net>, Greg Kurz <groug@kaod•org>,
Vivek Goyal <vgoyal@redhat•com>
Subject: Re: [PATCH v2 6/7] 9p/trans_virtio: support larger msize values
Date: Wed, 22 Sep 2021 13:42:18 +0200 [thread overview]
Message-ID: <2845466.DzA3qLHUVI@silver> (raw)
In-Reply-To: <f31e80bc67774d08f8d3bfb7ca0a970eeb369ca5.1632156835.git.linux_oss@crudebyte.com>
On Montag, 20. September 2021 18:44:13 CEST Christian Schoenebeck wrote:
> The virtio transport supports by default a 9p 'msize' of up to
> approximately 500 kB. This patch adds support for larger 'msize'
> values by resizing the amount of scatter/gather lists if required.
>
> Signed-off-by: Christian Schoenebeck <linux_oss@crudebyte•com>
> ---
> net/9p/trans_virtio.c | 57 +++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 57 insertions(+)
>
> diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
> index 0db8de84bd51..4cb75f45aa15 100644
> --- a/net/9p/trans_virtio.c
> +++ b/net/9p/trans_virtio.c
> @@ -200,6 +200,31 @@ static struct virtqueue_sg *vq_sg_alloc(unsigned int
> nsgl) return vq_sg;
> }
>
> +/**
> + * vq_sg_resize - resize passed virtqueue scatter/gather lists to the
> passed + * amount of lists
> + * @_vq_sg: scatter/gather lists to be resized
> + * @nsgl: new amount of scatter/gather lists
> + */
> +static int vq_sg_resize(struct virtqueue_sg **_vq_sg, unsigned int nsgl)
> +{
> + struct virtqueue_sg *vq_sg;
> +
> + BUG_ON(!_vq_sg || !nsgl);
> + vq_sg = *_vq_sg;
> + if (vq_sg->nsgl == nsgl)
> + return 0;
> +
> + /* lazy resize implementation for now */
> + vq_sg = vq_sg_alloc(nsgl);
> + if (!vq_sg)
> + return -ENOMEM;
> +
> + kfree(*_vq_sg);
> + *_vq_sg = vq_sg;
> + return 0;
> +}
> +
> /**
> * p9_virtio_close - reclaim resources of a channel
> * @client: client instance
> @@ -771,6 +796,10 @@ p9_virtio_create(struct p9_client *client, const char
> *devname, char *args) struct virtio_chan *chan;
> int ret = -ENOENT;
> int found = 0;
> +#if !defined(CONFIG_ARCH_NO_SG_CHAIN)
> + size_t npages;
> + size_t nsgl;
> +#endif
>
> if (devname == NULL)
> return -EINVAL;
> @@ -793,6 +822,34 @@ p9_virtio_create(struct p9_client *client, const char
> *devname, char *args) return ret;
> }
>
> + /*
> + * if user supplied an 'msize' option that's larger than what this
> + * transport supports by default, then try to allocate more sg lists
> + */
> + if (client->msize > client->trans_maxsize) {
> +#ifdef CONFIG_ARCH_NO_SG_CHAIN
> + pr_info("limiting 'msize' to %d because architecture does not "
> + "support chained scatter gather lists\n",
> + client->trans_maxsize);
> +#else
> + npages = DIV_ROUND_UP(client->msize, PAGE_SIZE);
> + if (npages > chan->p9_max_pages)
> + npages = chan->p9_max_pages;
> + nsgl = DIV_ROUND_UP(npages, SG_USER_PAGES_PER_LIST);
> + if (nsgl > chan->vq_sg->nsgl) {
> + /*
> + * if resize fails, no big deal, then just
> + * continue with default msize instead
> + */
> + if (!vq_sg_resize(&chan->vq_sg, nsgl)) {
> + client->trans_maxsize =
> + PAGE_SIZE *
> + ((nsgl * SG_USER_PAGES_PER_LIST) - 3);
> + }
> + }
Maybe an ...
} else {
pr_info(...);
}
would be useful here to explain the user why transport refrained from
increasing its max size even though user's msize option demanded it.
> +#endif /* CONFIG_ARCH_NO_SG_CHAIN */
> + }
> +
> client->trans = (void *)chan;
> client->status = Connected;
> chan->client = client;
next prev parent reply other threads:[~2021-09-22 11:42 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-20 16:43 [PATCH v2 0/7] net/9p: remove msize limit in virtio transport Christian Schoenebeck
2021-09-20 16:43 ` [PATCH v2 1/7] net/9p: show error message if user 'msize' cannot be satisfied Christian Schoenebeck
2021-09-20 16:43 ` [PATCH v2 2/7] 9p/trans_virtio: separate allocation of scatter gather list Christian Schoenebeck
2021-09-20 16:43 ` [PATCH v2 3/7] 9p/trans_virtio: turn amount of sg lists into runtime info Christian Schoenebeck
2021-09-20 16:44 ` [PATCH v2 4/7] 9p/trans_virtio: introduce struct virtqueue_sg Christian Schoenebeck
2021-09-22 11:25 ` Christian Schoenebeck
2021-09-20 16:44 ` [PATCH v2 5/7] net/9p: add trans_maxsize to struct p9_client Christian Schoenebeck
2021-09-20 16:44 ` [PATCH v2 6/7] 9p/trans_virtio: support larger msize values Christian Schoenebeck
2021-09-22 11:42 ` Christian Schoenebeck [this message]
2021-09-20 16:44 ` [PATCH v2 7/7] 9p/trans_virtio: resize sg lists to whatever is possible Christian Schoenebeck
2021-09-22 11:56 ` Christian Schoenebeck
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