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

[Arseniy Krasnov]

On 20.12.2022 13:38, Stefano Garzarella wrote:
> 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! I'll fix it(just forgot about README) and send v6 with 'net-next' tag when net-next will be opened
> 
> Thanks,
> Stefano
>