[ssh_x509] read network data directly to the packet input buffer ... no way!

[ssh_x509 at roumenpetrov.info]

ssh_x509 at roumenpetrov.info wrote:
> ssh_x509 at roumenpetrov.info wrote:
>> Hello,
>>
>> One of OpenSSH 8.9 (2022-02-23) new features is to "read network data directly to the packet input buffer instead of indirectly via a small stack buffer. Provides a modest performance improvement."
[SNIP]

> As result from tests I decided do not activate functionality that writes directly into packet input buffer. It is available but not build by default.

For protocol. Each "test" configuration was run nine time. Build configuration (buffer size &use of direct write) is selected in a random way. Each test starts with sync command, delay from one second in GUI with open terminal window and editor.

Tests are for sftp upload or download. In additionally was performed a cross test:
----
SFTP download 64M from localhost
PKIX-PKIX    PKIX-BSD    BSD-PKIX    BSD-BSD
9.43        53.06        76.91        548.97
----
Result is in time in seconds as first is client. So mixing buffer sizes with up to 256k buffer in direct write lеаd to catastrophic performance in OpenBSD implementation.
BSD server - 5.6 time slow!
BSD client - 8.2 time slow!
BSD client&server - 58.2 time slow!!! This is not percent. As percent result is 5721.53%.


Regards,
Roumen Petrov