On Thu, May 07, 2026 at 07:33:40AM -0700, Jakub Kicinski wrote:
On Thu, 7 May 2026 14:59:13 +0200 Stefano Garzarella wrote:
>well if you want to support pathological cases such as 1 byte messages
>that would mean like 100x reduction no?
Yep, but since this patch is already merged, IMHO that is better than
losing data in those pathological cases.
We can revert if you think that the risk of regression is high..
Please LMK soon, we can do it before patch reaches Linus.
Some tests in tools/testing/vsock/vsock_test.c are failing with this
patch applied.
Test 18 are failing sometime in this way (I guess because we are
dropping packets):
18 - SOCK_STREAM MSG_ZEROCOPY...hash mismatch
Test 22 is failing 100% in this way:
22 - SOCK_STREAM virtio credit update + SO_RCVLOWAT...send failed:
Resource temporarily unavailable
With my followup patch adding also advertisement to the other peer
(still draft locally, waiting for Michael proposal) I saw 22 failing,
because tests expects that can use the entire buf_alloc, but now we are
reducing it. So IMO we should do like in `__sock_set_rcvbuf()` and
double the buffer size, or at least digest an overhead equal to the
buffer size set by the user via SO_VM_SOCKETS_BUFFER_SIZE (yeah,
AF_VSOCK has it owns sockopt since the beginning :-().
With that approach tests are passing, but I'd like to stress a bit more
that patch. I'll send it tomorrow as fixup of this patch, or if you
prefer to revert, I'll send as standalone.
Thanks,
Stefano
