On 12/30/2015 11:09, Christophe Milard wrote:
I'll try to be clearer:
If a second linux process (ODP task) called B does a pktio_lookup()
on a pktio opened by first linux process A (onother ODP task
implemented as unix process), it will be returned the pktio_handle
that A created, and will start using the file descriptor stored there.
B will use the file descriptor created by A.
I must be missing something. But that is doomed to fail in my eyes.
On 30 December 2015 at 08:57, Maxim Uvarov <[email protected]
<mailto:[email protected]>> wrote:
On 12/30/2015 10:42, Christophe Milard wrote:
My question relates to pktio when ODP tasks are implemented as
unix processes (as opposed to threads).
I can see that the pktio_entry struct used is allocated as
shared mem.
If I take the socket pktio as an example, the socket file
descriptor is stored in th pktio struct.
In other words, the socket file descriptor is shared between
all ODP task (i.e. unix processes).
This does makes sense only if:
1)The process creating and using the pktio is unique (shared
mem is not necessary but won't hurt)
2) the file descriptor is created before fork(), i.e.
pktio_open() is performed before ODP threads are created. Always.
Yes, item 2 is true.
Maxim.
Are there any rules like this about the pktio handle usage?
If a pktio handle is supposed to be reachable at any time by
any task (at worse case, a process A creates a pktio handle
and passes it to another processes B and C which performs io
on the handle opened by A), then It looks like we have a
problem...
I have a similar situation where a PCI dev (including quite a
few file descriptors) is used, and I hoped I could see from
the socket example how this is to be handled... but I am not
sure...
what am I missing...?
Thanks,
Christophe.
Not sure that I understand what exact problem is...
In general you should never transmit any odp handle to other
process. And task should relay only on return of odp_pktio_open()
call.
Threads can look up pktio with odp_pktio_t odp_pktio_lookup(const
char *dev) call.
Of course if you do
pktio = odp_pktio_open("eth0")
fork();
Than you will have 2 process with same pktio handle value if you
print it. That happens that fork() just clones memory of parent
process to child. But you can not do another pktio2 =
odp_pktio_open("eth1") and transmit it to second process and
expect that it will work.
The same thing with file and socket descriptors.
Maxim.
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