Re: Problem with smbdirect rw credits and initiator_depth

[Stefan Metzmacher <metze@samba.org>]

Am 05.12.25 um 13:21 schrieb Namjae Jeon:
>>> 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.
> I have attached v2 and v3 logs. Let me know if you need something more,

Thanks!

A difference is that max_sgl_rd=3 is non 0, so it likely
takes a different code path for compared to irdma (roce) and rxe.
This can also be forced with the force_mr=1 module parameter of ib_core...

It would be good to see captures while testing with rxe for ksmbd.

>>>
>>> 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.
> /mnt# bpftrace ksmbd-rdma-xmit.bt
> Attaching 1 probe...
> 
> The absence of any output after Attaching 1 probe... indicates that
> the smb_direct_rdma_xmit function has not been called ?

It seems to, does the client has smb signing required?

I tested ksmbd with 'server signing = mandatory' and
as far as I remember copying a 5GB iso from and to
the server worked fine.

I used this bpftrace script to show that smbdirect
was really used, but without RDMA read/write offload:


kprobe:smb_direct_rdma_xmit {
         printf("%s: %s pid=%d %s: BEGIN\n", strftime("%F %H:%M:%S", nsecs(sw_tai)), comm, pid, func)
}

kretprobe:smb_direct_rdma_xmit {
         //printf("%s: %s pid=%d %s: RETURN\n", strftime("%F %H:%M:%S", nsecs(sw_tai)), comm, pid, func)
}
kprobe:read_done {
         printf("%s: %s pid=%d %s\n", strftime("%F %H:%M:%S", nsecs(sw_tai)), comm, pid, func)
}

kprobe:write_done {
         printf("%s: %s pid=%d %s\n", strftime("%F %H:%M:%S", nsecs(sw_tai)), comm, pid, func)
}

kprobe:smb2_write {
         printf("%s: %s pid=%d %s\n", strftime("%F %H:%M:%S", nsecs(sw_tai)), comm, pid, func)
}
kprobe:smb2_read {
         printf("%s: %s pid=%d %s\n", strftime("%F %H:%M:%S", nsecs(sw_tai)), comm, pid, func)
}