On 4/2/19 11:25 AM, Jerin Jacob Kollanukkaran wrote:
On Tue, 2019-04-02 at 10:36 +0300, Andrew Rybchenko wrote:
On 4/2/19 3:47 AM, Jerin Jacob Kollanukkaran wrote:
On Mon, 2019-04-01 at 10:30 +0300, Andrew Rybchenko wrote:
External Email
On 3/31/19 7:25 PM, Pavan Nikhilesh Bhagavatula wrote:
From: Pavan Nikhilesh <pbhagavat...@marvell.com>
The `rte_eth_dma_zone_reserve()` is generally used to create HW
rings.
In some scenarios when a driver needs to reconfigure the ring
size
since the named memzone already exists it returns the previous
memzone
without checking if a different sized ring is requested.
Introduce a check to see if the ring size requested is
different
from the
previously created memzone length.
Fixes: 719dbebceb81 ("xen: allow determining DOM0 at runtime")
Cc: sta...@dpdk.org
Signed-off-by: Pavan Nikhilesh <pbhagavat...@marvell.com>
---
lib/librte_ethdev/rte_ethdev.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/lib/librte_ethdev/rte_ethdev.c
b/lib/librte_ethdev/rte_ethdev.c
index 12b66b68c..4ae12e43b 100644
--- a/lib/librte_ethdev/rte_ethdev.c
+++ b/lib/librte_ethdev/rte_ethdev.c
@@ -3604,9 +3604,12 @@ rte_eth_dma_zone_reserve(const struct
rte_eth_dev *dev, const char *ring_name,
}
mz = rte_memzone_lookup(z_name);
- if (mz)
+ if (mz && (mz->len == size))
return mz;
+ if (mz)
+ rte_memzone_free(mz);
NACK
I really don't like that API which should reserve does free if
requested
size does not match previously allocated.
Why? Is due to API name?
1. The problem really exists. The problem is bad and it very good
that you
caught it and came up with a patch. Many thanks.
2. Silently free and reallocate memory is bad. Memory could be
used/mapped etc.
If I understand it correctly, Its been used while configuring
the device and it is per queue, If so, Is there any case where
memory in use in parallel in real world case with DPDK?
"in real world case with DPDK" is very fragile justification.
I simply don't want to dig in this way since it is very easy to make
a mistake or simply false assumption.
3. As an absolute minimum if we accept the behaviour it must be
documented
in the function description.
If so,
Can we have rte_eth_dma_zone_reservere_with_resize() then ?
or any another name, You would like to have?
4. I'd prefer an error if different size (or bigger) memzone is
requested,
but I understand that it can break existing drivers.
Thomas, Ferruh, what do you think?
I understand the motivation, but I don't think the solution is
correct.
What you think it has correct solution then?
See above plus handling in drivers or dedicated function with
better name as you suggest above.
Handling in driver means return error?
Yes.
Regarding API, Yes, We can add new API. What we will do that exiting
driver. Is up to driver maintainers to use the new API. I am fine with
either approach, Just asking the opinion.
You have mine, but I'd like to know what other ethdev maintainers
think about it.
Obviously, We can not allocate max ring size in init time.
If the NIC has support for 64K HW ring, We will be wasting too much
as
it is per queue.
Yes, I agree that it is an overkill.
net/sfc tries to carefully free/reserve on NIC/queues reconfigure.
Many thanks,
Andrew.
