[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH 2/2] net: netmap: avoid mmap() when ports use th
From: |
Vincenzo Maffione |
Subject: |
Re: [Qemu-devel] [PATCH 2/2] net: netmap: avoid mmap() when ports use the same shared memory area |
Date: |
Fri, 22 Jan 2016 09:35:38 +0100 |
No, you're right, nm_mmap() is not defined for all netmap versions.
It will take a while for us to decide how to manage this. Would it be
possible to go ahead with patch 1/2 only (I will reissue the patch
series)?
Cheers,
Vincenzo
2016-01-14 4:25 GMT+01:00 Jason Wang <address@hidden>:
>
>
> On 01/08/2016 09:15 PM, Vincenzo Maffione wrote:
>> With this patch, nm_open() does not mmap() the netmap device. This
>> operation is performed separately only if the memory area of the
>> port just opened was not known before.
>> A global list of netmap clients is kept to check when matches
>> occur.
>>
>> Signed-off-by: Vincenzo Maffione <address@hidden>
>> ---
>> net/netmap.c | 38 +++++++++++++++++++++++++++++++++++++-
>> 1 file changed, 37 insertions(+), 1 deletion(-)
>>
>> diff --git a/net/netmap.c b/net/netmap.c
>> index 27295ab..6a4c01c 100644
>> --- a/net/netmap.c
>> +++ b/net/netmap.c
>> @@ -49,8 +49,12 @@ typedef struct NetmapState {
>> bool write_poll;
>> struct iovec iov[IOV_MAX];
>> int vnet_hdr_len; /* Current virtio-net header length.
>> */
>> + QTAILQ_ENTRY(NetmapState) next;
>> } NetmapState;
>>
>> +static QTAILQ_HEAD(, NetmapState) netmap_clients =
>> + QTAILQ_HEAD_INITIALIZER(netmap_clients);
>> +
>> #ifndef __FreeBSD__
>> #define pkt_copy bcopy
>> #else
>> @@ -78,6 +82,23 @@ pkt_copy(const void *_src, void *_dst, int l)
>> #endif /* __FreeBSD__ */
>>
>> /*
>> + * find nm_desc parent with same allocator
>> + */
>> +static struct nm_desc *
>> +netmap_find_memory(struct nm_desc *nmd)
>> +{
>> + NetmapState *s;
>> +
>> + QTAILQ_FOREACH(s, &netmap_clients, next) {
>> + if (nmd->req.nr_arg2 == s->nmd->req.nr_arg2) {
>> + return s->nmd;
>> + }
>> + }
>> +
>> + return NULL;
>> +}
>> +
>> +/*
>> * Open a netmap device. We assume there is only one queue
>> * (which is the case for the VALE bridge).
>> */
>> @@ -86,10 +107,11 @@ static struct nm_desc *netmap_open(const
>> NetdevNetmapOptions *nm_opts,
>> {
>> struct nm_desc *nmd;
>> struct nmreq req;
>> + int ret;
>>
>> memset(&req, 0, sizeof(req));
>>
>> - nmd = nm_open(nm_opts->ifname, &req, NETMAP_NO_TX_POLL,
>> + nmd = nm_open(nm_opts->ifname, &req, NETMAP_NO_TX_POLL |
>> NM_OPEN_NO_MMAP,
>> NULL);
>> if (nmd == NULL) {
>> error_setg_errno(errp, errno, "Failed to nm_open() %s",
>> @@ -97,6 +119,17 @@ static struct nm_desc *netmap_open(const
>> NetdevNetmapOptions *nm_opts,
>> return NULL;
>> }
>>
>> + /* Check if we already have a nm_desc that uses the same memory as the
>> one
>> + * just opened, so that nm_mmap() can skip mmap() and inherit from
>> parent.
>> + */
>> + ret = nm_mmap(nmd, netmap_find_memory(nmd));
>
> Looks like I could not find nm_mmap() definition in neither qemu or
> freebsd source. Is there anything missed?
>
>> + if (ret) {
>> + error_setg_errno(errp, errno, "Failed to nm_mmap() %s",
>> + nm_opts->ifname);
>> + nm_close(nmd);
>> + return NULL;
>> + }
>> +
>> return nmd;
>> }
>>
>> @@ -321,6 +354,8 @@ static void netmap_cleanup(NetClientState *nc)
>> netmap_poll(nc, false);
>> nm_close(s->nmd);
>> s->nmd = NULL;
>> +
>> + QTAILQ_REMOVE(&netmap_clients, s, next);
>> }
>>
>> /* Offloading manipulation support callbacks. */
>> @@ -423,6 +458,7 @@ int net_init_netmap(const NetClientOptions *opts,
>> s->rx = NETMAP_RXRING(nmd->nifp, 0);
>> s->vnet_hdr_len = 0;
>> pstrcpy(s->ifname, sizeof(s->ifname), netmap_opts->ifname);
>> + QTAILQ_INSERT_TAIL(&netmap_clients, s, next);
>> netmap_read_poll(s, true); /* Initially only poll for reads. */
>>
>> return 0;
>
--
Vincenzo Maffione