Re: [RFC PATCH v5 0/4] vsock: update tools and error handling

[Stefano Garzarella]

On Tue, Dec 20, 2022 at 07:16:38AM +0000, Arseniy Krasnov wrote:
> Patchset consists of two parts:
>
> 1) Kernel patch
> One patch from Bobby Eshleman. I took single patch from Bobby:
> https://lore.kernel.org/lkml/d81818b868216c774613dd03641fcfe63cc55a45
> .1660362668.git.bobby.eshleman@xxxxxxxxxxxxx/ and use only part for
> af_vsock.c, as VMCI and Hyper-V parts were rejected.
>
> I used it, because for SOCK_SEQPACKET big messages handling was broken -
> ENOMEM was returned instead of EMSGSIZE. And anyway, current logic which
> always replaces any error code returned by transport to ENOMEM looks
> strange for me also(for example in EMSGSIZE case it was changed to
> ENOMEM).
>
> 2) Tool patches
> Since there is work on several significant updates for vsock(virtio/
> vsock especially): skbuff, DGRAM, zerocopy rx/tx, so I think that this
> patchset will be useful.
>
> This patchset updates vsock tests and tools a little bit. First of all
> it updates test suite: two new tests are added. One test is reworked
> message bound test. Now it is more complex. Instead of sending 1 byte
> messages with one MSG_EOR bit, it sends messages of random length(one
> half of messages are smaller than page size, second half are bigger)
> with random number of MSG_EOR bits set. Receiver also don't know total
> number of messages. Message bounds control is maintained by hash sum
> of messages length calculation. Second test is for SOCK_SEQPACKET - it
> tries to send message with length more than allowed. I think both tests
> will be useful for DGRAM support also.
>
> Third thing that this patchset adds is small utility to test vsock
> performance for both rx and tx. I think this util could be useful as
> 'iperf'/'uperf', because:
> 1) It is small comparing to 'iperf' or 'uperf', so it very easy to add
>   new mode or feature to it(especially vsock specific).
> 2) It allows to set SO_RCVLOWAT and SO_VM_SOCKETS_BUFFER_SIZE option.
>   Whole throughtput depends on both parameters.
> 3) It is located in the kernel source tree, so it could be updated by
>   the same patchset which changes related kernel functionality in vsock.
>
> I used this util very often to check performance of my rx zerocopy
> support(this tool has rx zerocopy support, but not in this patchset).
>
> Here is comparison of outputs from three utils: 'iperf', 'uperf' and
> 'vsock_perf'. In all three cases sender was at guest side. rx and
> tx buffers were always 64Kb(because by default 'uperf' uses 8K).
>
> iperf:
>
>   [ ID] Interval           Transfer     Bitrate
>   [  5]   0.00-10.00  sec  12.8 GBytes  11.0 Gbits/sec sender
>   [  5]   0.00-10.00  sec  12.8 GBytes  11.0 Gbits/sec receiver
>
> uperf:
>
>   Total     16.27GB /  11.36(s) =    12.30Gb/s       23455op/s
>
> vsock_perf:
>
>   tx performance: 12.301529 Gbits/s
>   rx performance: 12.288011 Gbits/s
>
> Results are almost same in all three cases.

Thanks for checking this!

> Patchset was rebased and tested on skbuff v8 patch from Bobby Eshleman:
> https://lore.kernel.org/netdev/20221215043645.3545127-1-bobby.eshleman@xxxxxxxxxxxxx/

I reviewed all the patches, in the last one there is just to update the 
README, so I think it is ready for net-next (when it will re-open).

Thanks,
Stefano