Re: Problem with smbdirect rw credits and initiator_depth

[Stefan Metzmacher <metze@samba.org>]

Am 05.12.25 um 03:33 schrieb Namjae Jeon:
> On Thu, Dec 4, 2025 at 6:40 PM Stefan Metzmacher <metze@samba.org> wrote:
>>
>> Hi Namjae,
> Hi Metze,
>>
>>> Okay, It seems like the issue has been improved in your v3 branch. If
>>> you send the official patches, I will test it more.
>>
>> It's good to have verified that for-6.18/ksmbd-smbdirect-regression-v3
>> on a 6.18 kernel behaves the same as with 6.17.9, as transport_rdma.c
>> is the same, but it doesn't really allow forward process on
>> the Mellanox problem.
>>
>> Can you at least post the dmesg output generated by this:
>> https://git.samba.org/?p=metze/linux/wip.git;a=commitdiff;h=7e724ebc58e986f4e101a55f4ab5e96912239918
>> Assuming that this wasn't triggered:
>> if (WARN_ONCE(needed > max_possible, "needed:%u > max:%u\n", needed, max_possible))
> I didn't know you wanted it. I will share it after office.
>>
>> Did you run the bpftrace command? Did it print a lot of
>> 'smb_direct_rdma_xmit' message over the whole time of the file copy?
> No, I didn't check it. but I will try this.
>>
>> Did you actually copied a file to or from the server?
> nod.

I asked what you were trying, not if it worked.

>>
>> Have you actually tested for-6.18/ksmbd-smbdirect-regression-v2,
>> as requested? As I was in hope that it would work in the
>> same way as for-6.18/ksmbd-smbdirect-regression-v3,
>> but with only a single patch reverted.
> I tested the v2 patch and the same issues still occurred, but they are
> gone in v3.
>>
>> I'll continue to fix the general problem that this works
>> for non Mellanox setups, as it seems it never worked at all :-(
> Smbdirect should work well on Mellanox NICs. As I said before, most
> people use this. I've rarely seen ksmbd users use smbdirect with
> non-Mellanox NICs. If you want to have a stable, long-term smbdirect
> feature on Samba, you'll need to have this device.

Yes, I'll try to buy two connectx cards, but it will take some
time until they will arrive.

And from what I found out last week while fixing ksmbd
to work with irdma in roce as well as rxe, to me was pure
luck that it worked with Mellanox.

>>
>> Where you testing with RoCEv2 or Infiniband?
> RoCEv2
>>
>> I think moving forward for Mellanox setups requires these steps:
>> - Test v1 vs. v2 and see that smb_direct_rdma_xmit is actually
>>     called at all. And see the dmesg output.
>> - Testing with Mellanox RoCEv2 on the client and rxe on
>>     the server, so that we can create a network capture with tcpdump.

Whould you be able to test with rxe on the ksmbd side?
Is it possible to disable both infiniband and roce on
the Mellanox nic? So that you can use rxe instead and
take a capture?

Thanks!
metze