Florin is correct. There is also a performance and/or scaling penalty
due to the need to handle both kernel socket based file descriptors and
VCL/VPP created file descriptors with the LD_PRELOAD callback functions.
Thanks,
-daw-
On 7/31/18 2:11 PM, Florin Coras wrote:
Hi Matt,
I’d say that trying to cover all possible combinations of POSIX calls
is the main issue. Also, statically linked applications won’t work
fine with ld_preload. But, I’ll let Dave provide more details since he
is more closely involved with the effort.
Florin
On Jul 31, 2018, at 7:01 AM, Matthew Smith <mgsm...@netgate.com
<mailto:mgsm...@netgate.com>> wrote:
Hi Florin and Dave,
I’m curious what problems were observed with the LD_PRELOAD
mechanism. Were there performance issues? Or was it too difficult to
try and cover different usage of POSIX calls? Or something else?
Thanks!
-Matt
On Jul 30, 2018, at 10:39 AM, Florin Coras <fcoras.li...@gmail.com
<mailto:fcoras.li...@gmail.com>> wrote:
Prashant,
Dave is exactly right. If you still want to try out the LDP layer, I
wouldn’t set a global LD_PRELOAD variable because that will end up
preloading all the applications and, inevitably, to some unsupported
usage patterns and crashes. Instead, start only your app with
LD_PRELOAD set, something like:
LD_PRELOAD=../vpp/build-root/install-vpp_debug-native/vpp/lib64/libvcl_ldpreload.so
<your_app>
Note that we’re exercising both the vcl and ldp layers with our test
infrastructure. So, you may also want to take a look at test_vcl for
more details on how we use the ldp layer.
Hope this helps,
Florin
On Jul 30, 2018, at 8:09 AM, Dave Wallace <dwallac...@gmail.com
<mailto:dwallac...@gmail.com>> wrote:
Prashant,
The VCL LD_PRELOAD library is experimental and only works with a
very limited set of legacy POSIX sockets applications (and only
with single workers).
The conclusion based on the results of the initial experimentation
with LD_PRELOAD is that it is not a viable mechanism for
accelerating legacy POSIX sockets based applications using the VPP
host stack. The current recommendation is to refactor legacy
applications to use the VCL API directly.
You should also be aware that the VCL infrastructure is in the
middle of being refactored at this time and thus the VCL API may
change. I'll let Florin, who is doing the refactoring, add his
input on the VCL API roadmap.
Thanks,
-daw-
On 7/30/2018 7:21 AM, Prashant Upadhyaya wrote:
Hi,
I have compiled VPP and it's running. I have an interface up and can
ping the IP applied there.
Now I am trying to bring up a legacy application TCP server (the one
which uses POSIX calls). So I set the LD_PRELOAD to point to
.../vpp/build-root/install-vpp_debug-native/vpp/lib64/libvcl_ldpreload.so
But the server application now crashes on startup.
Even the ldd command starts crashing.
Can somebody point me to the correct set of steps to be used for
LD_PRELOAD to bring up my legacy tcp server which will then engage the
VPP TCP stack instead of the kernel's
Regards
-Prashant
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